Bio


Dessi completed her PhD at York University in Toronto, Canada under the supervision of Dr. Michael Riddell in 2018. Her PhD research focused on strategies to reduce dysglycemia around exercise in adults with type 1 diabetes. Dessi is currently an Instructor at Stanford working under the supervision of Dr. David Maahs. Her research focuses on exercise physiology and blood glucose management in type 1 diabetes.

Academic Appointments


Honors & Awards


  • ISPAD-JDRF Research Fellowship, International Society for Pediatric and Adolescent Diabetes (ISPAD) (Dec 2020)
  • Vanier Canada Graduate Scholarship, CIHR (2015-2018)

Professional Education


  • Doctor of Philosophy, York University (2018)
  • Master of Science, York University (2014)
  • Bachelor of Kinesiology, Brock University (2011)

All Publications


  • Late Afternoon Vigorous Exercise Increases Post-Meal but Not Overnight Hypoglycemia in Adults with Type 1 Diabetes Managed with Automated Insulin Delivery. Diabetes technology & therapeutics Morrison, D., Paldus, B., Zaharieva, D. P., Lee, M. H., Vogrin, S., Jenkins, A. J., La Gerche, A., MacIsaac, R. J., McAuley, S. A., Ward, G. M., Colman, P. G., Smart, C. E., Seckold, R., Grosman, B., Roy, A., King, B., Riddell, M. C., O'Neal, D. N. 2022

    Abstract

    AIM To assess evening and overnight hypoglycemia risk following late afternoon exercise compared with a non-exercise control day in adults with type 1 diabetes using automated insulin delivery (AID). METHODS Thirty adults with type 1 diabetes (Mean [SD] Age 38[9] Years; 14Female; HbA1c 7.1[1.0] % / 54[11 ] mmol/mol ) using AID (Minimed 670G) performed in random order 40-minutes high-intensity (HIE), resistance (RE), and moderate-intensity (MIE) exercise each separated by >1 week. Exercise commenced at ~16:00. A standardized meal was eaten at ~20:40. Hypoglycemic events were defined as a continuous glucose monitor (CGM) reading <70mg/dL for ≥15 min. Four-hour post-evening meal and overnight (MN-06:00) CGM metrics for exercise were compared with the prior non-exercise (control) day. RESULTS There was no severe hypoglycemia. Between 00:00-06:00, the proportion of nights with hypoglycemia did not differ post-exercise vs control for HIE (18% vs. 11%; p=0.688), RE (4% vs. 14%; p=0.375) and MIE (7% vs. 14%; p=0.625). Time in Range (70-180mg/dL), >75% for all nights, did not differ between exercise conditions and control. Hypoglycemia episodes post-meal following exercise vs. control did not differ for HIE (22% vs 7%; p=0.219) and MIE (10% vs. 14%; p>0.999) but were greater post RE (39% vs. 10%; p=0.012). CONCLUSIONS Overnight TIR was excellent with AID without an increase in hypoglycemia post-exercise between 00:00-06:00 compared with non-exercise days. In contrast the risk for hypoglycemia was increased following the first meal post-RE, suggesting the importance of greater vigilance and specific guidelines for meal-time dosing, particularly with vigorous RE.

    View details for DOI 10.1089/dia.2022.0279

    View details for PubMedID 36094458

  • Relationship Between Moderate-to-Vigorous Physical Activity and Glycemia Among Young Adults with Type 1 Diabetes and Overweight or Obesity: Results from the Advancing Care for Type 1 Diabetes and Obesity Network (ACT1ON) Study. Diabetes technology & therapeutics Muntis, F. R., Igudesman, D., Cristello Sarteau, A., Thomas, J., Arrizon-Ruiz, N., Hooper, J., Addala, A., Crandell, J. L., Riddell, M. C., Maahs, D. M., Pratley, R. E., Corbin, K., Mayer-Davis, E. J., Zaharieva, D. P. 2022

    Abstract

    AIMS: Using data from the ACT1ON study, we conducted secondary analyses to assess the relationship between minutes of moderate-to-vigorous physical activity (MVPA) and glycemia in adults with type 1 diabetes (T1D) and overweight or obesity.MATERIALS AND METHODS: Participants (n=66) with T1D provided measures of glycemia (HbA1c, percent of time below range [TBR, <70mg/dL], time-in-range [TIR, 70-180mg/dL], time above range [TAR, >180mg/dL]) and self-reported physical activity (Global Physical Activity Questionnaire (GPAQ), Previous Day Physical Activity Recalls (PDPAR)) at baseline, 3-, 6-, & 9-months post-intervention. Wearable activity data was available for a subset of participants (n=27). Associations were estimated using mixed effects regression models adjusted for design, demographic, clinical, and dietary covariates.RESULTS: Among young adults aged 19-30 with a baseline HbA1c of 7.9 ± 1.4% and BMI of 30.3 (IQR 27.9, 33.8), greater habitual weekly MVPA minutes were associated with higher HbA1c via the GPAQ (p<0.01) and wearable activity data (p=0.01). We did not observe a significant association between habitual MVPA and any continuous glucose monitoring metrics. Using PDPAR data, however, we observed that greater daily MVPA minutes were associated with more TAR (p<0.01) and reduced TIR (p<0.01) on the day following reported physical activity.CONCLUSIONS: Among young adults with T1D and overweight or obesity, increased MVPA was associated with worsened glycemia. As physical activity is vital to cardiovascular health and weight management, additional research is needed to determine how to best support young adults with T1D and overweight or obesity in their efforts to increase physical activity.

    View details for DOI 10.1089/dia.2022.0253

    View details for PubMedID 35984327

  • Advancements and future directions in the teamwork, targets, technology, and tight control-the 4T study: improving clinical outcomes in newly diagnosed pediatric type 1 diabetes. Current opinion in pediatrics Zaharieva, D. P., Bishop, F. K., Maahs, D. M., 4T study research team 2022; 34 (4): 423-429

    Abstract

    PURPOSE OF REVIEW: The benefits of intensive diabetes management have been established by the Diabetes Control and Complications Trial. However, challenges with optimizing glycemic management in youth with type 1 diabetes (T1D) remain across pediatric clinics in the United States. This article will review our Teamwork, Targets, Technology, and Tight Control (4T) study that implements emerging diabetes technology into clinical practice with a team approach to sustain tight glycemic control from the onset of T1D and beyond to optimize clinical outcomes.RECENT FINDINGS: During the 4T Pilot study and study 1, our team-based approach to intensive target setting, education, and remote data review has led to significant improvements in hemoglobin A1c throughout the first year of T1D diagnosis in youth, as well as family and provider satisfaction.SUMMARY: The next steps include refinement of the current 4T study 1, developing a business case, and broader implementation of the 4T study. In study 2, we are including a more pragmatic cadence of remote data review and disseminating exercise education and activity tracking to both English- and Spanish-speaking families. The overall goal is to create and implement a translatable program that can facilitate better outcomes for pediatric clinics across the USA.

    View details for DOI 10.1097/MOP.0000000000001140

    View details for PubMedID 35836400

  • "Much more convenient, just as effective:" Experiences of starting continuous glucose monitoring remotely following Type 1 diabetes diagnosis. Diabetic medicine : a journal of the British Diabetic Association Tanenbaum, M. L., Zaharieva, D. P., Addala, A., Prahalad, P., Hooper, J. A., Leverenz, B., Cortes, A. L., Arrizon-Ruiz, N., Pang, E., Bishop, F., Maahs, D. M. 2022: e14923

    Abstract

    Initiating continuous glucose monitoring (CGM) shortly after Type 1 diabetes diagnosis has glycemic and quality of life benefits for youth with Type 1 diabetes and their families. The SARS-CoV-2 pandemic led to a rapid shift to virtual delivery of CGM initiation visits. We aimed to understand parents' experiences receiving virtual care to initiate CGM within 30 days of diagnosis.We held focus groups and interviews using a semi-structured interview guide with parents of youth who initiated CGM over telehealth within 30 days of diagnosis during the SARS-CoV-2 pandemic. Questions aimed to explore experiences of starting CGM virtually. Groups and interviews were audio-recorded, transcribed, and analyzed using thematic analysis.Participants were 16 English-speaking parents (age 43±6 years; 63% female) of 15 youth (age 9±4 years; 47% female; 47% non-Hispanic White, 20% Hispanic, 13% Asian, 7% Black, 13% other). They described multiple benefits of the virtual visit including convenient access to high-quality care; integrating Type 1 diabetes care into daily life; and being in the comfort of home. A minority experienced challenges with virtual care delivery; most preferred the virtual format. Participants expressed that clinics should offer a choice of virtual or in-person to families initiating CGM in the future.Most parents appreciated receiving CGM initiation education via telehealth and felt it should be an option offered to all families. Further efforts can continue to enhance CGM initiation teaching virtually to address identified barriers.

    View details for DOI 10.1111/dme.14923

    View details for PubMedID 35899591

  • More hypoglycemia not associated with increasing estimated adiposity in youth with type 1 diabetes. Pediatric research Sarteau, A. C., Kahkoska, A. R., Crandell, J., Igudesman, D., Corbin, K. D., Kichler, J. C., Maahs, D. M., Muntis, F., Pratley, R., Seid, M., Zaharieva, D., Mayer-Davis, E. 2022

    Abstract

    BACKGROUND: Despite the widespread clinical perception that hypoglycemia may drive weight gain in youth with type 1 diabetes (T1D), there is an absence of published evidence supporting this hypothesis.METHODS: We estimated the body fat percentage (eBFP) of 211 youth (HbA1c 8.0-13.0%, age 13-16) at baseline, 6, and 18 months of the Flexible Lifestyles Empowering Change trial using validated equations. Group-based trajectory modeling assigned adolescents to sex-specific eBFP groups. Using baseline 7-day blinded continuous glucose monitoring data, "more" vs. "less" percent time spent in hypoglycemia was defined by cut-points using sample median split and clinical guidelines. Adjusted logistic regression estimated the odds of membership in an increasing eBFP group comparing youth with more vs. less baseline hypoglycemia.RESULTS: More time spent in clinical hypoglycemia (defined by median split) was associated with 0.29 the odds of increasing eBFP in females (95% CI: 0.12, 0.69; p=0.005), and 0.33 the odds of stable/increasing eBFP in males (95% CI: 0.14, 0.78; p=0.01).CONCLUSIONS: Hypoglycemia may not be a major driver of weight gain in US youth with T1D and HbA1c ≥8.0. Further studies in different sub-groups are needed to clarify for whom hypoglycemia may drive weight gain and focus future etiological studies and interventions.IMPACT: We contribute epidemiological evidence that hypoglycemia may not be a major driver of weight gain in US youth with type 1 diabetes and HbA1c ≥8.0% and highlight the need for studies to prospectively test this hypothesis rooted in clinical perception. Future research should examine the relationship between hypoglycemia and adiposity together with psychosocial, behavioral, and other clinical factors among sub-groups of youth with type 1 diabetes (i.e., who meet glycemic targets or experience a frequency/severity of hypoglycemia above a threshold) to further clarify for whom hypoglycemia may drive weight gain and progress etiological understanding of and interventions for healthy weight maintenance.

    View details for DOI 10.1038/s41390-022-02129-1

    View details for PubMedID 35729217

  • Strengths and Challenges of Closed-Loop Insulin Delivery During Exercise in People With Type 1 Diabetes: Potential Future Directions. Journal of diabetes science and technology Paldus, B., Morrison, D., Lee, M., Zaharieva, D. P., Riddell, M. C., O'Neal, D. N. 2022: 19322968221088327

    Abstract

    Exercise has many physical and psychological benefits and is recommended for people with type 1 diabetes; however, there are many barriers to exercise, including glycemic instability and fear of hypoglycemia. Closed-loop (CL) systems have shown benefit in the overall glycemic management of type 1 diabetes, including improving HbA1c levels and reducing the incidence of nocturnal hypoglycemia; however, these systems are challenged by the rapidly changing insulin needs with exercise. This commentary focuses on the principles, strengths, and challenges of CL in the management of exercise, and discusses potential approaches, including the use of additional physiological signals, to address their shortcomings in the pursuit of fully automated CL systems.

    View details for DOI 10.1177/19322968221088327

    View details for PubMedID 35466723

  • Design of the advancing care for type 1 diabetes and obesity network energy metabolism and sequential multiple assignment randomized trial nutrition pilot studies: An integrated approach to develop weight management solutions for individuals with type 1 diabetes. Contemporary clinical trials Corbin, K. D., Igudesman, D., Addala, A., Casu, A., Crandell, J., Kosorok, M. R., Maahs, D. M., Pokaprakarn, T., Pratley, R. E., Souris, K. J., Thomas, J., Zaharieva, D. P., Mayer-Davis, E. 2022: 106765

    Abstract

    Young adults with type 1 diabetes (T1D) often have difficulty co-managing weight and glycemia. The prevalence of overweight and obesity among individuals with T1D now parallels that of the general population and contributes to dyslipidemia, insulin resistance, and risk for cardiovascular disease. There is a compelling need to develop a program of research designed to optimize two key outcomes-weight management and glycemia-and to address the underlying metabolic processes and behavioral challenges unique to people with T1D. For an intervention addressing these dual outcomes to be effective, it must be appropriate to the unique metabolic phenotype of T1D, and to biological and behavioral responses to glycemia (including hypoglycemia) that relate to weight management. The intervention must also be safe, feasible, and accepted by young adults with T1D. In 2015, we established a consortium called ACT1ON: Advancing Care for Type 1 Diabetes and Obesity Network, a transdisciplinary team of scientists at multiple institutions. The ACT1ON consortium designed a multi-phase study which, in parallel, evaluated the mechanistic aspects of the unique metabolism and energy requirements of individuals with T1D, alongside a rigorous adaptive behavioral intervention to simultaneously facilitate weight management while optimizing glycemia. This manuscript describes the design of our integrative study-comprised of an inpatient mechanistic phase and an outpatient behavioral phase-to generate metabolic, behavioral, feasibility, and acceptability data to support a future, fully powered sequential, multiple assignment, randomized trial to evaluate the best approaches to prevent and treat obesity while co-managing glycemia in people with T1D. Clinicaltrials.gov identifiers: NCT03651622 and NCT03379792. The present study references can be found here: https://clinicaltrials.gov/ct2/show/NCT03651622 https://clinicaltrials.gov/ct2/show/NCT03379792?term=NCT03379792&draw=2&rank=1 Submission Category: "Study Design, Statistical Design, Study Protocols".

    View details for DOI 10.1016/j.cct.2022.106765

    View details for PubMedID 35460915

  • Mindfulness, disordered eating, and impulsivity in relation to glycemia among adolescents with type 1 diabetes and suboptimal glycemia from the Flexible Lifestyles Empowering Change (FLEX) Intervention Trial. Pediatric diabetes Irwin, A., Igudesman, D., Crandell, J., Kichler, J. C., Kahkoska, A. R., Burger, K., Zaharieva, D. P., Addala, A., Mayer-Davis, E. J. 2022

    Abstract

    OBJECTIVE: To assess the relationship between mindfulness and glycemia among adolescents with type 1 diabetes (T1D) with suboptimal glycemia, and evaluate the potential mediation by ingestive behaviors, including disordered eating, and impulsivity.METHODS: We used linear mixed models for hemoglobin A1c (HbA1c) and linear regression for continuous glucose monitoring (CGM) to study the relationship of mindfulness [Child and Adolescent Mindfulness Measure (CAMM)] and glycemia in adolescents with T1D from the 18-month Flexible Lifestyles Empowering Change (FLEX) trial. We tested for mediation of the mindfulness-glycemia relationship by ingestive behaviors, including disordered eating (Diabetes Eating Problem Survey - Revised), restrained eating, and emotional eating (Dutch Eating Behavior Questionnaire); and impulsivity (total, attentional, and motor, Barrett Impulsiveness Scale).RESULTS: At baseline, participants (n=152) had a mean age of 14.9 ±1.1years and HbA1c of 9.4 ±1.2% [79±13mmol/mol]. The majority of adolescents were non-Hispanic white (83.6%), 50.7% were female, and 73.0% used insulin pumps. From adjusted mixed models, a 5-point increase in mindfulness scores was associated with a -0.19% (95%CI -0.29, -0.08, p=0.0006) reduction in HbA1c. We did not find statistically significant associations between mindfulness and CGM metrics. Mediation of the relationship between mindfulness and HbA1c by ingestive behaviors and impulsivity was not found to be statistically significant.CONCLUSIONS: Among adolescents with T1D and suboptimal glycemia, increased mindfulness was associated with lower HbA1c levels. Future studies may consider mindfulness-based interventions as a component of treatment for improving glycemia among adolescents with T1D, though more data are needed to assess feasibility and efficacy. Words: 250/250 This article is protected by copyright. All rights reserved.

    View details for DOI 10.1111/pedi.13334

    View details for PubMedID 35297136

  • Advances in Exercise and Nutrition as Therapy in Diabetes. Diabetes technology & therapeutics Zaharieva, D. P., Riddell, M. C. 2022; 24 (S1): S129-S142

    View details for DOI 10.1089/dia.2022.2508

    View details for PubMedID 35475701

  • A Randomized Crossover Trial Comparing Glucose Control During Moderate-Intensity, High-Intensity, and Resistance Exercise With Hybrid Closed-Loop Insulin Delivery While Profiling Potential Additional Signals in Adults With Type 1 Diabetes DIABETES CARE Paldus, B., Morrison, D., Zaharieva, D. P., Lee, M. H., Jones, H., Obeyesekere, V., Lu, J., Vogrin, S., La Gerche, A., McAuley, S. A., MacIsaac, R. J., Jenkins, A. J., Ward, G. M., Colman, P., Smart, C. M., Seckold, R., King, B. R., Riddell, M. C., O'Neal, D. N. 2022; 45 (1): 194-203

    Abstract

    To compare glucose control with hybrid closed-loop (HCL) when challenged by high intensity exercise (HIE), moderate intensity exercise (MIE), and resistance exercise (RE) while profiling counterregulatory hormones, lactate, ketones, and kinetic data in adults with type 1 diabetes.This study was an open-label multisite randomized crossover trial. Adults with type 1 diabetes undertook 40 min of HIE, MIE, and RE in random order while using HCL (Medtronic MiniMed 670G) with a temporary target set 2 h prior to and during exercise and 15 g carbohydrates if pre-exercise glucose was <126 mg/dL to prevent hypoglycemia. Primary outcome was median (interquartile range) continuous glucose monitoring time-in-range (TIR; 70-180 mg/dL) for 14 h post-exercise commencement. Accelerometer data and venous glucose, ketones, lactate, and counterregulatory hormones were measured for 280 min post-exercise commencement.Median TIR was 81% (67, 93%), 91% (80, 94%), and 80% (73, 89%) for 0-14 h post-exercise commencement for HIE, MIE, and RE, respectively (n = 30), with no difference between exercise types (MIE vs. HIE; P = 0.11, MIE vs. RE, P = 0.11; and HIE vs. RE, P = 0.90). Time-below-range was 0% for all exercise bouts. For HIE and RE compared with MIE, there were greater increases, respectively, in noradrenaline (P = 0.01 and P = 0.004), cortisol (P < 0.001 and P = 0.001), lactate (P ≤ 0.001 and P ≤ 0.001), and heart rate (P = 0.007 and P = 0.015). During HIE compared with MIE, there were greater increases in growth hormone (P = 0.024).Under controlled conditions, HCL provided satisfactory glucose control with no difference between exercise type. Lactate, counterregulatory hormones, and kinetic data differentiate type and intensity of exercise, and their measurement may help inform insulin needs during exercise. However, their potential utility as modulators of insulin dosing will be limited by the pharmacokinetics of subcutaneous insulin delivery.

    View details for DOI 10.2337/dc21-1593

    View details for Web of Science ID 000797976500035

    View details for PubMedID 34789504

  • Current and Novel Strategies to Reduce Fear of Hypoglycemia as a Barrier to Physical Activity in Adults and Youth With Type 1 Diabetes. Canadian journal of diabetes Zaharieva, D. P., Addala, A. 2022; 46 (1): 1-2

    View details for DOI 10.1016/j.jcjd.2021.12.004

    View details for PubMedID 35144756

  • Teamwork, Targets, Technology, and Tight Control in Newly Diagnosed Type 1 Diabetes: Pilot 4T Study. The Journal of clinical endocrinology and metabolism Prahalad, P., Ding, V. Y., Zaharieva, D. P., Addala, A., Johari, R., Scheinker, D., Desai, M., Hood, K., Maahs, D. M. 2021

    Abstract

    CONTEXT: Youth with type 1 diabetes (T1D) do not meet hemoglobin A1c (HbA1c) targets.OBJECTIVE: To assess HbA1c outcomes in children with new onset T1D enrolled in the Teamwork, Targets, Technology and Tight Control (4T) Study.METHOD: HbA1c levels were compared between the 4T and Historical cohorts. HbA1c differences between cohorts were estimated using locally estimated scatter plot smoothing (LOESS). The change from nadir HbA1c (month 4) to 12 months post-diagnosis was estimated by cohort using a piecewise mixed effects regression model accounting for age at diagnosis, sex, ethnicity, and insurance type.SETTING AND PARTICIPANTS: We recruited 135 youth with newly diagnosed T1D at Stanford Children's Health.INTERVENTION: Starting July 2018, all youth within the first month of T1D diagnosis were offered continuous glucose monitoring (CGM) initiation and remote CGM data review was added in March 2019.MAIN OUTCOME MEASURE: HbA1c.RESULTS: HbA1c at 6, 9, and 12 months post-diagnosis was lower in the 4T cohort than in the Historic cohort (-0.54%, -0.52%, and -0.58%, respectively). Within the 4T cohort, HbA1c at 6, 9, and 12 months post-diagnosis was lower in those patients with Remote Monitoring than those without (-0.14%, -0.18%, -0.14%, respectively). Multivariable regression analysis showed that the 4T cohort experienced a significantly lower increase in HbA1c between months 4 and 12 (p < 0.001).CONCLUSIONS: A technology-enabled team-based approach to intensified new onset education involving target setting, CGM initiation, and remote data review significantly decreased HbA1c in youth with T1D 12 months post-diagnosis.

    View details for DOI 10.1210/clinem/dgab859

    View details for PubMedID 34850024

  • Opportunities and challenges in closed-loop systems in type 1 diabetes. The lancet. Diabetes & endocrinology Wilson, L. M., Jacobs, P. G., Riddell, M. C., Zaharieva, D. P., Castle, J. R. 2021

    View details for DOI 10.1016/S2213-8587(21)00289-8

    View details for PubMedID 34762835

  • Comparable glucose control with fast-acting insulin aspart versus insulin aspart using a second-generation hybrid closed-loop system during exercise. Diabetes technology & therapeutics Morrison, D., Zaharieva, D., Lee, M. H., Paldus, B., Vogrin, S., Grosman, B., Roy, A., Kurtz, N., O'Neal, D. N. 2021

    Abstract

    Background We aimed to compare glucose control with FiAsp versus insulin aspart following moderate-intensity exercise (MIE) and high-intensity exercise (HIE) using a second-generation closed-loop (CL) system in people with type 1 diabetes. Materials and methods This randomised crossover study compared FiAsp versus insulin aspart over four sessions during MIE and HIE with CL insulin delivery by the MiniMed TM Medtronic Advanced hybrid CL system. Participants were randomly assigned FiAsp and insulin aspart each for six weeks and within each period performed, in random order, 40min MIE (~50% VO2max) and HIE (6x2min ~80% VO2max; 5min recovery). The primary outcome was continuous glucose monitoring (CGM) time in range (TIR, 3.9-10.0mmol/L) for 24h following exercise. Results Sixteen adults (nine male; age 48 [37, 57] years; HbA1c 7.0 [6.4, 7.2] %; duration diabetes 30 [17, 41] years) were recruited. In the 24h post-exercise, median TIR was >81%, time in hypoglycemia (<3.9mmol/L) was <4% and time in hyperglycemia (>10mmol/L) was <17% for both exercise conditions and insulin formations, with no significant differences between insulins (P>0.05). In the 2h post-exercise and overnight the TIR approached 100% for all conditions. Conclusions There were no differences in TIR during and 24h after MIE or HIE when comparing insulin aspart with FiAsp delivered by a second-generation CL system. Insulin formations with an offset in action greater than FiAsp are needed to provide a meaningful improvement in CL glucose control with exercise. Trial registration: ACTRN12619000469112.

    View details for DOI 10.1089/dia.2021.0221

    View details for PubMedID 34524022

  • Fast-Acting Insulin Aspart Versus Insulin Aspart Using a Second-Generation Hybrid Closed-Loop System in Adults With Type 1 Diabetes: A Randomized, Open-Label, Crossover Trial. Diabetes care Lee, M. H., Paldus, B., Vogrin, S., Morrison, D., Zaharieva, D. P., Lu, J., Jones, H. M., Netzer, E., Robinson, L., Grosman, B., Roy, A., Kurtz, N., Ward, G. M., MacIsaac, R. J., Jenkins, A. J., O'Neal, D. N. 2021

    Abstract

    OBJECTIVE: To evaluate glucose control using fast-acting insulin aspart (faster aspart) compared with insulin aspart (IAsp) delivered by the MiniMed Advanced Hybrid Closed-Loop (AHCL) system in adults with type 1 diabetes.RESEARCH DESIGN AND METHODS: In this randomized, open-label, crossover study, participants were assigned to receive faster aspart or IAsp in random order. Stages 1 and 2 comprised of 6 weeks in closed loop, preceded by 2 weeks in open loop. This was followed by stage 3, whereby participants changed directly back to the insulin formulation used in stage 1 for 1 week in closed loop. Participants chose their own meals except for two standardized meal tests, a missed meal bolus and late meal bolus. The primary outcome was the percentage of time sensor glucose values were from 70 to 180 mg/dL (time in range; [TIR]).RESULTS: Twenty-five adults (52% male) were recruited; the median (interquartile range) age was 48 (37, 57) years, and the median HbA1c was 7.0% (6.6, 7.2) (53 [49, 55] mmol/mol). Faster aspart demonstrated greater overall TIR compared with IAsp (82.3% [78.5, 83.7] vs. 79.6% [77.0, 83.4], respectively; mean difference 1.9% [0.5, 3.3]; P = 0.007). Four-hour postprandial glucose TIR was higher using faster aspart compared with IAsp for all meals combined (73.6% [69.4, 80.2] vs. 72.1% [64.5, 78.5], respectively; median difference 3.5% [1.0, 7.3]; P = 0.003). There was no ketoacidosis or severe hypoglycemia.CONCLUSIONS: Faster aspart safely improved glucose control compared with IAsp in a group of adults with well-controlled type 1 diabetes using AHCL. The modest improvement was mainly related to mealtime glycemia. While the primary outcome demonstrated statistical significance, the clinical impact may be small, given an overall difference in TIR of 1.9%.

    View details for DOI 10.2337/dc21-0814

    View details for PubMedID 34362816

  • First Randomized Controlled Trial of Hybrid Closed Loop Versus Multiple Daily Injections or Insulin Pump using Self-Monitoring of Blood Glucose in Free-Living Adults with Type 1 Diabetes Undertaking Exercise. Journal of diabetes science and technology Paldus, B., Lee, M. H., Morrison, D., Zaharieva, D. P., Jones, H., Obeyesekere, V., Lu, J., Vogrin, S., LaGerche, A., McAuley, S. A., MacIsaac, R. J., Jenkins, A. J., Ward, G. M., Colman, P., O'Neal, D. N. 2021: 19322968211035110

    View details for DOI 10.1177/19322968211035110

    View details for PubMedID 34315271

  • Advances in Exercise and Nutrition as Therapy in Diabetes. Diabetes technology & therapeutics Riddell, M. C., Davis, E. A., Mayer-Davis, E. J., Kahkoska, A., Zaharieva, D. P. 2021; 23 (S2): S131-S142

    View details for DOI 10.1089/dia.2021.2509

    View details for PubMedID 34061626

  • Glucose management for exercise using continuous glucose monitoring: should sex and prandial state be additional considerations? Reply to Yardley JE and Sigal RJ [letter]. Diabetologia Moser, O. n., Riddell, M. C., Eckstein, M. L., Adolfsson, P. n., Rabasa-Lhoret, R. n., van den Boom, L. n., Gillard, P. n., Nørgaard, K. n., Oliver, N. S., Zaharieva, D. P., Battelino, T. n., de Beaufort, C. n., Bergenstal, R. M., Buckingham, B. n., Cengiz, E. n., Deeb, A. n., Heise, T. n., Heller, S. n., Kowalski, A. J., Leelarathna, L. n., Mathieu, C. n., Stettler, C. n., Tauschmann, M. n., Thabit, H. n., Wilmot, E. G., Sourij, H. n., Smart, C. E., Jacobs, P. G., Bracken, R. M., Mader, J. K. 2021

    View details for DOI 10.1007/s00125-020-05374-3

    View details for PubMedID 33538843

  • Clinically serious hypoglycemia is rare and not associated with time-in-range in youth with new-onset type 1 diabetes. The Journal of clinical endocrinology and metabolism Addala, A., Zaharieva, D. P., Gu, A. J., Prahalad, P., Scheinker, D., Buckingham, B., Hood, K. K., Maahs, D. M. 2021

    Abstract

    Early initiation of continuous glucose monitoring (CGM) is advocated for youth with type 1 diabetes (T1D). Data to guide CGM use on time-in-range (TIR), hypoglycemia, and the role of partial clinical remission (PCR) are limited. Our aims were to assess whether: 1) an association between increased TIR and hypoglycemia exists, and 2) how time in hypoglycemia varies by PCR status.We analyzed 80 youth who were started on CGM shortly after T1D diagnosis and were followed for up to 1-year post-diagnosis. TIR and hypoglycemia rates were determined by CGM data and retrospectively analyzed. PCR was defined as (visit-HbA1c)+(4*units/kg/day) <9.Youth were started on CGM 8.0 (IQR 6.0-13.0) days post-diagnosis. Time spent <70mg/dL remained low despite changes in TIR (highest TIR 74.6±16.7%, 2.4±2.4% hypoglycemia at 1 month post-diagnosis; lowest TIR 61.3±20.3%, 2.1±2.7% hypoglycemia at 12 months post-diagnosis). No events of severe hypoglycemia occurred. Hypoglycemia was rare and there was minimal difference for PCR versus non-PCR youth (54-70mg/dL: 1.8% vs 1.2%, p=0.04; <54mg/dL: 0.3% vs 0.3%, p=0.55). Approximately 50% of the time spent in hypoglycemia was in the 65-70mg/dL range.As TIR gradually decreased over 12 months post-diagnosis, hypoglycemia was limited with no episodes of severe hypoglycemia. Hypoglycemia rates did not vary in a clinically meaningful manner by PCR status. With CGM being started earlier, consideration needs to be given to modifying CGM hypoglycemia education, including alarm settings. These data support a trial in the year post-diagnosis to determine alarm thresholds for youth who wear CGM.

    View details for DOI 10.1210/clinem/dgab522

    View details for PubMedID 34265059

  • "I was ready for it at the beginning": Parent experiences with early introduction of continuous glucose monitoring following their child's Type 1 diabetes diagnosis. Diabetic medicine : a journal of the British Diabetic Association Tanenbaum, M. L., Zaharieva, D. P., Addala, A. n., Ngo, J. n., Prahalad, P. n., Leverenz, B. n., New, C. n., Maahs, D. M., Hood, K. K. 2021: e14567

    Abstract

    To capture the experience of parents of youth with recent onset Type 1 diabetes who initiated use of continuous glucose monitoring (CGM) technology soon after diagnosis, which is a new practice.Focus groups and individual interviews were conducted with parents of youth with Type 1 diabetes who had early initiation of CGM as part of a new clinical protocol. Interviewers used a semi-structured interview guide to elicit feedback and experiences with starting CGM within 30 days of diagnosis, and the benefits and barriers they experienced when adjusting to this technology. Groups and interviews were audio-recorded, transcribed, and analyzed using content analysis.Participants were 16 parents (age 44.13±8.43 years; 75% female; 56.25% non-Hispanic White) of youth (age 12.38±4.15 years; 50% female; 50% non-Hispanic White; diabetes duration 10.35±3.89 months) who initiated CGM 11.31±7.33 days after diabetes diagnosis. Overall, parents reported high levels of satisfaction with starting CGM within a month of diagnosis and described a high level of reliance on the technology to help manage their child's diabetes. All participants recommended early CGM initiation for future families and were committed to continue using the technology for the foreseeable future, provided that insurance covered it.Parents experienced CGM initiation shortly after their child's Type 1 diabetes diagnosis as a highly beneficial and essential part of adjusting to living with diabetes.

    View details for DOI 10.1111/dme.14567

    View details for PubMedID 33772862

  • The Development of an Exercise Advisor App for Type 1 Diabetes: Digitization Facilitates More Individualized Guidance. Journal of diabetes science and technology McGaugh, S. M., Edwards, S., Wolpert, H., Zaharieva, D. P., Gulati, N., Riddell, M. C. 2020: 1932296820979811

    Abstract

    Maintaining blood glucose levels in the target range during exercise can be onerous for people with type 1 diabetes (T1D). Using evidence-based research and consensus guidelines, we developed an exercise advisor app to reduce some of the burden associated with diabetes management during exercise. The app will guide the user on carbohydrate feeding strategies and insulin management strategies before, during, and after exercise and provide targeted and individualized recommendations. As a basis for the recommendations, the decision trees for the app use various factors including the type of insulin regimen, time of activity, previous insulin boluses, and current glucose level. The app is designed to meet the various needs of people with T1D for different activities to promote safe exercise practices.

    View details for DOI 10.1177/1932296820979811

    View details for PubMedID 33345601

  • Carbohydrate Requirements for Prolonged, Fasted Exercise With and Without Basal Rate Reductions in Adults With Type 1 Diabetes on Continuous Subcutaneous Insulin Infusion. Diabetes care McGaugh, S. M., Zaharieva, D. P., Pooni, R., D'Souza, N. C., Vienneau, T., Ly, T. T., Riddell, M. C. 2020

    Abstract

    OBJECTIVE: Exercising while fasted with type 1 diabetes facilitates weight loss; however, the best strategy to maintain glucose stability remains unclear.RESEARCH DESIGN AND METHODS: Fifteen adults on continuous subcutaneous insulin infusion completed three sessions of fasted walking (120 min at 45% VOmax) in a randomized crossover design: 50% basal rate reduction, set 90 min pre-exercise (-90min50%BRR); usual basal rate with carbohydrate intake of (0.3 g/kg/h) (CHO-only); and combined 50% basal rate reduction set at exercise onset with carbohydrate intake of 0.3 g/kg/h (Combo).RESULTS: Combo had a smaller change in glucose (5 ± 47 mg/dL) versus CHO-only (-49 ± 61 mg/dL, P = 0.03) or -90min50%BRR (-34 ± 45 mg/dL). The -90min50%BRR strategy produced higher beta-hydroxybutyrate levels (0.4 ± 0.3 vs. 0.1 ± 0.1 mmol/L) and greater fat oxidation (0.51 ± 0.2 vs. 0.39 ± 0.1 g/min) than CHO-only (both P < 0.05).CONCLUSIONS: All strategies examined produced stable glycemia for fasted exercise, but a 50% basal rate reduction, set 90 min pre-exercise, eliminates carbohydrate needs and enhances fat oxidation better than carbohydrate feeding with or without a basal rate reduction set at exercise onset.

    View details for DOI 10.2337/dc20-1554

    View details for PubMedID 33328284

  • Differences in Physiological Responses to Cardiopulmonary Exercise Testing in Adults With and Without Type 1 Diabetes: A Pooled Analysis. Diabetes care Eckstein, M. L., Farinha, J. B., McCarthy, O., West, D. J., Yardley, J. E., Bally, L., Zueger, T., Stettler, C., Boff, W., Reischak-Oliveira, A., Riddell, M. C., Zaharieva, D. P., Pieber, T. R., Muller, A., Birnbaumer, P., Aziz, F., Brugnara, L., Haahr, H., Zijlstra, E., Heise, T., Sourij, H., Roden, M., Hofmann, P., Bracken, R. M., Pesta, D., Moser, O. 2020

    Abstract

    OBJECTIVE: To investigate physiological responses to cardiopulmonary exercise (CPX) testing in adults with type 1 diabetes compared with age-, sex-, and BMI-matched control participants without type 1 diabetes.RESEARCH DESIGN AND METHODS: We compared results from CPX tests on a cycle ergometer in individuals with type 1 diabetes and control participants without type 1 diabetes. Parameters were peak and threshold variables of VO2, heart rate, and power output. Differences between groups were investigated through restricted maximum likelihood modeling and post hoc tests. Differences between groups were explained by stepwise linear regressions (P < 0.05).RESULTS: Among 303 individuals with type 1 diabetes (age 33 [interquartile range 22; 43] years, 93 females, BMI 23.6 [22; 26] kg/m2, HbA1c 6.9% [6.2; 7.7%] [52 (44; 61) mmol/mol]), VO2peak (32.55 [26.49; 38.72] vs. 42.67 ± 10.44 mL/kg/min), peak heart rate (179 [170; 187] vs. 184 [175; 191] beats/min), and peak power (216 [171; 253] vs. 245 [200; 300] W) were lower compared with 308 control participants without type 1 diabetes (all P < 0.001). Individuals with type 1 diabetes displayed an impaired degree and direction of the heart rate-to-performance curve compared with control participants without type 1 diabetes (0.07 [-0.75; 1.09] vs. 0.66 [-0.28; 1.45]; P < 0.001). None of the exercise physiological responses were associated with HbA1c in individuals with type 1 diabetes.CONCLUSIONS: Individuals with type 1 diabetes show altered responses to CPX testing, which cannot be explained by HbA1c. Intriguingly, the participants in our cohort were people with recent-onset type 1 diabetes; heart rate dynamics were altered during CPX testing.

    View details for DOI 10.2337/dc20-1496

    View details for PubMedID 33184152

  • Differences in physiological Response to cardio-pulmonary Graded Exercise Stress Test in People with Type 1 Diabetes and Non-diabetics - A pooled Analysis Eckstein, M., Farinha, J., McCarthy, O., West, D., Yardley, J., Bally, L., Zueger, T., Stettler, C., Boff, W., Reischak-Oliveira, A., Riddell, M., Zaharieva, D., Pieber, T., Mueller, A., Birnbaumer, P., Aziz, F., Brugnara, L., Haahr, H., Zijlstra, E., Heise, T., Sourij, H., Roden, M., Hofmann, P., Bracken, R., Pesta, D., Moser, O. SPRINGER WIEN. 2020: S347–S348
  • Glucose Management during physical Activity/Sport by Using continuous Glucose Meters (CGM/isCGM) in Type 1 Diabetes - EASD/ISPAD Position Statement, supported by ADA and JDRF Moser, O., Riddell, M. C., Eckstein, M. L., Adolfsson, P., Rabasa-Lhoret, R., van den Boom, L., Gillard, P., Norgaard, K., Oliver, N. S., Zaharieva, D. P., Battelino, T., De Beaufort, C., Bergenstal, R. M., Buckingham, B., Cengiz, E., Deeb, A., Heise, T., Heller, S., Kowalski, A. J., Leelarathna, L., Mathieu, C., Stettler, C., Tauschmann, M., Thabit, H., Wilmot, E. G., Sourij, H., Smart, C. E., Jacobs, P. G., Bracken, R. M., Mader, J. K. SPRINGER WIEN. 2020: S340–S341
  • Weight Management in Youth with Type 1 Diabetes and Obesity: Challenges and Possible Solutions. Current obesity reports Zaharieva, D. P., Addala, A., Simmons, K. M., Maahs, D. M. 2020

    Abstract

    PURPOSE OF REVIEW: This review highlights challenges associated with weight management in children and adolescents with type 1 diabetes (T1D). Our purpose is to propose potential solutions to improve weight outcomes in youth with T1D.RECENT FINDINGS: A common barrier to weight management in T1D is reluctance to engage in exercise for fear of hypoglycemia. Healthcare practitioners generally provide limited guidance for insulin dosing and carbohydrate modifications to maintain stable glycemia during exercise. Adherence to dietary guidelines is associated with improved glycemia; however, youth struggle to meet recommendations. When psychosocial factors are addressed in combination with glucose trends, this often leads to successful T1D management. Newer medications also hold promise to potentially aid in glycemia and weight management, but further research is necessary. Properly addressing physical activity, nutrition, pharmacotherapy, and psychosocial factors while emphasizing weight management may reduce the likelihood of obesity development and its perpetuation in this population.

    View details for DOI 10.1007/s13679-020-00411-z

    View details for PubMedID 33108635

  • Glucose management for exercise using continuous glucose monitoring (CGM) and intermittently scanned CGM (isCGM) systems in type 1 diabetes: position statement of the European Association for the Study of Diabetes (EASD) and of the International Society for Pediatric and Adolescent Diabetes (ISPAD) endorsed by JDRF and supported by the American Diabetes Association (ADA). Pediatric diabetes Moser, O., Riddell, M. C., Eckstein, M. L., Adolfsson, P., Rabasa-Lhoret, R., van den Boom, L., Gillard, P., Norgaard, K., Oliver, N. S., Zaharieva, D. P., Battelino, T., de Beaufort, C., Bergenstal, R. M., Buckingham, B., Cengiz, E., Deeb, A., Heise, T., Heller, S., Kowalski, A. J., Leelarathna, L., Mathieu, C., Stettler, C., Tauschmann, M., Thabit, H., Wilmot, E. G., Sourij, H., Smart, C. E., Jacobs, P. G., Bracken, R. M., Mader, J. K. 2020

    Abstract

    Physical exercise is an important component in the management of type 1 diabetes across the lifespan. Yet, acute exercise increases the risk of dysglycaemia, and the direction of glycaemic excursions depends, to some extent, on the intensity and duration of the type of exercise. Understandably, fear of hypoglycaemia is one of the strongest barriers to incorporating exercise into daily life. Risk of hypoglycaemia during and after exercise can be lowered when insulin-dose adjustments are made and/or additional carbohydrates are consumed. Glycaemic management during exercise has been made easier with continuous glucose monitoring (CGM) and intermittently scanned continuous glucose monitoring (isCGM) systems; however, because of the complexity of CGM and isCGM systems, both individuals with type 1 diabetes and their healthcare professionals may struggle with the interpretation of given information to maximise the technological potential for effective use around exercise (ie, before, during and after). This position statement highlights the recent advancements in CGM and isCGM technology, with a focus on the evidence base for their efficacy to sense glucose around exercise and adaptations in the use of these emerging tools, and updates the guidance for exercise in adults, children and adolescents with type 1 diabetes.

    View details for DOI 10.1111/pedi.13105

    View details for PubMedID 33047481

  • Glucose management for exercise using continuous glucose monitoring (CGM) and intermittently scanned CGM (isCGM) systems in type 1 diabetes: position statement of the European Association for the Study of Diabetes (EASD) and of the International Society for Pediatric and Adolescent Diabetes (ISPAD) endorsed by JDRF and supported by the American Diabetes Association (ADA). Diabetologia Moser, O., Riddell, M. C., Eckstein, M. L., Adolfsson, P., Rabasa-Lhoret, R., van den Boom, L., Gillard, P., Norgaard, K., Oliver, N. S., Zaharieva, D. P., Battelino, T., de Beaufort, C., Bergenstal, R. M., Buckingham, B., Cengiz, E., Deeb, A., Heise, T., Heller, S., Kowalski, A. J., Leelarathna, L., Mathieu, C., Stettler, C., Tauschmann, M., Thabit, H., Wilmot, E. G., Sourij, H., Smart, C. E., Jacobs, P. G., Bracken, R. M., Mader, J. K. 2020

    Abstract

    Physical exercise is an important component in the management of type 1 diabetes across the lifespan. Yet, acute exercise increases the risk of dysglycaemia, and the direction of glycaemic excursions depends, to some extent, on the intensity and duration of the type of exercise. Understandably, fear of hypoglycaemia is one of the strongest barriers to incorporating exercise into daily life. Risk of hypoglycaemia during and after exercise can be lowered when insulin-dose adjustments are made and/or additional carbohydrates are consumed. Glycaemic management during exercise has been made easier with continuous glucose monitoring (CGM) and intermittently scanned continuous glucose monitoring (isCGM) systems; however, because of the complexity of CGM and isCGM systems, both individuals with type 1 diabetes and their healthcare professionals may struggle with the interpretation of given information to maximise the technological potential for effective use around exercise (i.e. before, during and after). This position statement highlights the recent advancements in CGM and isCGM technology, with a focus on the evidence base for their efficacy to sense glucose around exercise and adaptations in the use of these emerging tools, and updates the guidance for exercise in adults, children and adolescents with type 1 diabetes. Graphical abstract.

    View details for DOI 10.1007/s00125-020-05263-9

    View details for PubMedID 33047169

  • The competitive athlete with type 1 diabetes. Diabetologia Riddell, M. C., Scott, S. N., Fournier, P. A., Colberg, S. R., Gallen, I. W., Moser, O., Stettler, C., Yardley, J. E., Zaharieva, D. P., Adolfsson, P., Bracken, R. M. 2020

    Abstract

    Regular exercise is important for health, fitness and longevity in people living with type 1 diabetes, and many individuals seek to train and compete while living with the condition. Muscle, liver and glycogen metabolism can be normal in athletes with diabetes with good overall glucose management, and exercise performance can be facilitated by modifications to insulin dose and nutrition. However, maintaining normal glucose levels during training, travel and competition can be a major challenge for athletes living with type 1 diabetes. Some athletes have low-to-moderate levels of carbohydrate intake during training and rest days but tend to benefit, from both a glucose and performance perspective, from high rates of carbohydrate feeding during long-distance events. This review highlights the unique metabolic responses to various types of exercise in athletes living with type 1 diabetes. Graphical abstract.

    View details for DOI 10.1007/s00125-020-05183-8

    View details for PubMedID 32533229

  • Clinically Significant Hypoglycemia Is Rare in Youth with T1D during Partial Clinical Remission Addala, A., Gu, A., Zaharieva, D., Prahalad, P., Buckingham, B. A., Scheinker, D., Maahs, D. M. AMER DIABETES ASSOC. 2020
  • Early Introduction of Continuous Glucose Monitoring Is Well Accepted by Youth and Parents Addala, A., Hanes, S., Zaharieva, D., New, C., Prahalad, P., Maahs, D. M., Hood, K. K., Tanenbaum, M. L. AMER DIABETES ASSOC. 2020
  • Newly Diagnosed Pediatric Patients with Type 1 Diabetes Show Steady Decline in Glucose Time-in-Range (TIR) over 1 Year: Pilot Study Zaharieva, D., Prahalad, P., Addala, A., Scheinker, D., Desai, M., Hood, K. K., Leverenz, B., Maahs, D. M. AMER DIABETES ASSOC. 2020
  • TITLE: CONTINUOUS GLUCOSE MONITORING VERSUS SELF-MONITORING OF BLOOD GLUCOSE TO ASSESS GLYCEMIA IN GESTATIONAL DIABETES. Diabetes technology & therapeutics Zaharieva, D., Teng, J. H., Ong, M. L., Lee, M. H., Paldus, B., Jackson, L., Holihan, C. A., Shub, A., Tipnis, S., Cohen, O., O'Neal, D. N., Krishnamurthy, B. 2020

    Abstract

    Gestational diabetes mellitus (GDM) management using self-monitoring blood glucose (SMBG) does not normalise pregnancy outcomes.We aimed to conduct an observational study to explore if Continuous Glucose Monitoring (CGM) could identify elevated glucose levels not apparent in women with GDM managed using SMBG.A 7-day masked-CGM (iPro, Medtronic) was performed within 2 weeks of GDM diagnosis, immediately post-GDM education but prior to insulin commencement as determined by SMBG. CGM data regarding hyperglycemia (sensor glucose >126 mg/dL [06:00-00:00hrs] and > 99 mg/dL [00:00-06:00hrs] for >10% of time), time with healthcare professionals (HCP), treatment, and pregnancy outcome were collected. Comparisons (Mann-Whitney test) were performed between subjects subsequently commenced on insulin versus those continued with diet and lifestyle measures alone.Ninety women of Mean (SD) gestational age weeks 27(1) were studied. Those prescribed insulin (n=34) compared with those managed with diet and lifestyle alone (n=56) had a greater time in hyperglycemia (p=0.0001). Of those not prescribed insulin, 35/56 (61%) breached CGM cut-offs between 00:00-06:00hrs; 11/56 (20%) breached 6.00-00.00hrs CGM cut-offs for >10% of the time; and 21/45 (47%) with optimal CGM glucose levels during the daytime spent >10% time in hyperglycaemia between 00.00-06:00 hrs. In contrast, SMBG measurements exceeded the clinical targets of <120mg/dL post-dinner in 5.4% and <100mg/dL fasting in 0% of the subjects.CGM provides a more comprehensive assessment of nocturnal hyperglycemia than SMBG and could improve targeting of interventions in GDM. Larger studies to better define CGM targets are required which once established will inform studies aimed at targeting nocturnal glucose levels.

    View details for DOI 10.1089/dia.2020.0073

    View details for PubMedID 32324046

  • No Disadvantage to Insulin Pump Off vs Pump On During Intermittent High-Intensity Exercise in Adults With Type 1 Diabetes. Canadian journal of diabetes Zaharieva, D. P., Cinar, A., Yavelberg, L., Jamnik, V., Riddell, M. C. 2020; 44 (2): 162-168

    Abstract

    Evidence suggests that patients with type 1 diabetes (T1D) performing aerobic exercise with their insulin pump connected (pump on) vs pump disconnected (pump off) have an increased risk of hypoglycemia. It has not been examined whether this risk remains during high-intensity exercise. This study compared the effects of pump on (50% basal insulin at exercise onset) vs pump off (0% basal insulin at exercise onset) on glucose concentrations during intermittent high-intensity exercise in adults with T1D and on patients' own perspective of their glycemia.Twelve adults with T1D using insulin pump therapy completed two 40-min intermittent high-intensity exercise bouts. Insulin adjustments included: 1) pump set to 50% of usual basal rate (pump on) or 2) pump suspended (pump off) during exercise, in random order. Blood glucose was recorded every 10 min during exercise and, after providing subjects with an initial reference glucose value before exercise, participants were asked to estimate their glucose during exercise.Glucose levels were higher in pump off (8.1±1.3 mmol/L) vs pump on (7.4±2.1 mmol/L) at exercise start (p<0.05), but were similar by the end of exercise (p=0.9). During exercise, hypoglycemia incidence did not differ between conditions (1 of 12 for both). However, the percentage of time in hypoglycemia at 12 h after exercise was 5±8% vs 1±2% for pump on vs pump off, respectively (p=0.3). Participants were better able to estimate their own glucose during pump on vs pump off (r2=0.46 vs r2=0.11).Pump on vs pump off at exercise onset showed no significant differences in blood glucose concentrations during 40 min of intermittent high-intensity exercise.

    View details for DOI 10.1016/j.jcjd.2019.05.015

    View details for PubMedID 31416695

  • Advances in Exercise, Physical Activity, and Diabetes. Diabetes technology & therapeutics Zaharieva, D. P., McGaugh, S., Davis, E. A., Riddell, M. C. 2020; 22 (S1): S109-S118

    View details for DOI 10.1089/dia.2020.2508

    View details for PubMedID 32069147

  • Glucose Control During Physical Activity and Exercise Using Closed Loop Technology in Adults and Adolescents with Type 1 Diabetes. Canadian journal of diabetes Zaharieva, D. P., Messer, L. H., Paldus, B. n., O'Neal, D. N., Maahs, D. M., Riddell, M. C. 2020

    Abstract

    Guidelines for safe exercise strategies exist for both pediatric and adult patients living with type 1 diabetes. The management of type 1 diabetes during exercise is complex, but making insulin dosing adjustments in advance of activity can yield positive outcomes and reduce the likelihood of hypoglycemia. Closed loop (also known as automated insulin delivery) systems are able to partially automate insulin delivery and can assist in exercise and overall management of type 1 diabetes. Current exercise guidelines, however, focus primarily on management strategies for patients using multiple daily injections or open loop insulin pump therapy. Closed loop systems require strategic approaches to type 1 diabetes management, including appropriate timing and duration of exercise targets and carbohydrates around exercise that have yet to be standardized. This review aims to showcase how closed loop technology has evolved over the last decade and summarizes a number of closed loop and exercise studies both in free-living conditions and clinical trials. This review also highlights strategies and approaches for exercise and type 1 diabetes management using closed loop systems. Some differences in closed loop strategies for exercise include the importance of pump suspension if disconnecting during exercise, fewer grams of uncovered carbohydrates before exercise and these should be taken close to exercise onset to avoid a rise in automated insulin delivery. A primary goal for future closed loop systems is to detect exercise without user input, so that patients are not required to preset exercise targets well in advance of activity, as are the current recommendations.

    View details for DOI 10.1016/j.jcjd.2020.06.003

    View details for PubMedID 33011134

  • Improving Clinical Outcomes in Newly Diagnosed Pediatric Type 1 Diabetes: Teamwork, Targets, Technology, and Tight Control-The 4T Study. Frontiers in endocrinology Prahalad, P. n., Zaharieva, D. P., Addala, A. n., New, C. n., Scheinker, D. n., Desai, M. n., Hood, K. K., Maahs, D. M. 2020; 11: 360

    Abstract

    Many youth with type 1 diabetes (T1D) do not achieve hemoglobin A1c (HbA1c) targets. The mean HbA1c of youth in the USA is higher than much of the developed world. Mean HbA1c in other nations has been successfully modified following benchmarking and quality improvement methods. In this review, we describe the novel 4T approach-teamwork, targets, technology, and tight control-to diabetes management in youth with new-onset T1D. In this program, the diabetes care team (physicians, nurse practitioners, certified diabetes educators, dieticians, social workers, psychologists, and exercise physiologists) work closely to deliver diabetes education from diagnosis. Part of the education curriculum involves early integration of technology, specifically continuous glucose monitoring (CGM), and developing a curriculum around using the CGM to maintain tight control and optimize quality of life.

    View details for DOI 10.3389/fendo.2020.00360

    View details for PubMedID 32733375

    View details for PubMedCentralID PMC7363838

  • Lag Time Remains with Newer Real-Time Continuous Glucose Monitoring Technology During Aerobic Exercise in Adults Living with Type 1 Diabetes. Diabetes technology & therapeutics Zaharieva, D. P., Turksoy, K., McGaugh, S. M., Pooni, R., Vienneau, T., Ly, T., Riddell, M. C. 2019; 21 (6): 313-321

    Abstract

    Background: Real-time continuous glucose monitoring (CGM) devices help detect glycemic excursions associated with exercise, meals, and insulin dosing in patients with type 1 diabetes (T1D). However, the delay between interstitial and blood glucose may result in CGM underestimating the true change in glycemia during activity. The purpose of this study was to examine CGM discrepancies during exercise and the meal postexercise versus self-monitoring of blood glucose (SMBG). Methods: Seventeen adults with T1D using insulin pump therapy and CGM completed 60 min of aerobic exercise on three occasions. A standardized meal was given 30 min postexercise. SMBG was measured during exercise and in recovery using OmniPod® Personal Diabetes Manager (PDM; Insulet, Billerica, MA) with built-in glucose meter (FreeStyle; Abbott Laboratories, Abbott Park, IL), while CGM was measured with Dexcom G4® with 505 algorithm (n = 4) or G5® (n = 13), which were calibrated with subjects' own PDM. Results: SMBG showed a large drop in glycemia during exercise, while CGM showed a lag of 12 ± 11 (mean ± standard deviation) minutes and bias of -7 ± 19 mg/dL/min during activity. Mean absolute relative difference (MARD) for CGM versus SMBG was 13 (6-22)% [median (interquartile range)] during exercise and 8 (5-14)% during mealtime. Clarke error grids showed CGM values were in zones A and B 94%-99% of the time for SMBG. Conclusion: In summary, the drop in CGM lags behind the drop in blood glucose during prolonged aerobic exercise by 12 ± 11 min, and MARD increases to 13 (6-22)% during exercise as well. Therefore, if hypoglycemia is suspected during exercise, individuals should confirm glucose levels with a capillary glucose measurement.

    View details for DOI 10.1089/dia.2018.0364

    View details for PubMedID 31059282

    View details for PubMedCentralID PMC6551983

  • Improved Open-Loop Glucose Control With Basal Insulin Reduction 90 Minutes Before Aerobic Exercise in Patients With Type 1 Diabetes on Continuous Subcutaneous Insulin Infusion. Diabetes care Zaharieva, D. P., McGaugh, S., Pooni, R., Vienneau, T., Ly, T., Riddell, M. C. 2019; 42 (5): 824-831

    Abstract

    To reduce exercise-associated hypoglycemia, individuals with type 1 diabetes on continuous subcutaneous insulin infusion typically perform basal rate reductions (BRRs) and/or carbohydrate feeding, although the timing and amount of BRRs necessary to prevent hypoglycemia are unclear. The goal of this study was to determine if BRRs set 90 min pre-exercise better attenuate hypoglycemia versus pump suspension (PS) at exercise onset.Seventeen individuals completed three 60-min treadmill exercise (∼50% of VO2peak) visits in a randomized crossover design. The insulin strategies included 1) PS at exercise onset, 2) 80% BRR set 90 min pre-exercise, and 3) 50% BRR set 90 min pre-exercise.Blood glucose level at exercise onset was higher with 50% BRR (191 ± 49 mg/dL) vs. 80% BRR (164 ± 41 mg/dL; P < 0.001) and PS (164 ± 45 mg/dL; P < 0.001). By exercise end, 80% BRR showed the smallest drop (-31 ± 58 mg/dL) vs. 50% BRR (-47 ± 50 mg/dL; P = 0.04) and PS (-67 ± 41 mg/dL; P < 0.001). With PS, 7 out of 17 participants developed hypoglycemia versus 1 out of 17 in both BRR conditions (P < 0.05). Following a standardized meal postexercise, glucose rose with PS and 50% BRR (both P < 0.05), but failed to rise with 80% BRR (P = 0.16). Based on interstitial glucose, overnight mean percent time in range was 83%, 83%, and 78%, and time in hypoglycemia was 2%, 1%, and 5% with 80% BRR, 50% BRR, and PS, respectively (all P > 0.05).Overall, a 50-80% BRR set 90 min pre-exercise improves glucose control and decreases hypoglycemia risk during exercise better than PS at exercise onset, while not compromising the postexercise meal glucose control.

    View details for DOI 10.2337/dc18-2204

    View details for PubMedID 30796112

  • Advances in Exercise, Physical Activity, and Diabetes Mellitus. Diabetes technology & therapeutics Teich, T., Zaharieva, D. P., Riddell, M. C. 2019; 21 (S1): S112-S122

    View details for DOI 10.1089/dia.2019.2509

    View details for PubMedID 30785316

  • Individual glucose responses to prolonged moderate intensity aerobic exercise in adolescents with type 1 diabetes: The higher they start, the harder they fall. Pediatric diabetes Riddell, M. C., Zaharieva, D. P., Tansey, M., Tsalikian, E., Admon, G., Li, Z., Kollman, C., Beck, R. W. 2019; 20 (1): 99-106

    Abstract

    To evaluate the pattern of change in blood glucose concentrations and hypoglycemia risk in response to prolonged aerobic exercise in adolescents with type 1 diabetes (T1D) that had a wide range in pre-exercise blood glucose concentrations.Individual blood glucose responses to prolonged (~60 minutes) moderate-intensity exercise were profiled in 120 youth with T1D.The mean pre-exercise blood glucose concentration was 178 ± 66 mg/dL, ranging from 69 to 396 mg/dL, while the mean change in glucose during exercise was -76 ± 55 mg/dL (mean ± SD), ranging from +83 to -257 mg/dL. Only 4 of 120 youth (3%) had stable glucose levels during exercise (ie, ± ≤10 mg/dL), while 4 (3%) had a rise in glucose >10 mg/dL, and the remaining (93%) had a clinically significant drop (ie, >10 mg/dL). A total of 53 youth (44%) developed hypoglycemia (≤70 mg/dL) during exercise. The change in glucose was negatively correlated with the pre-exercise glucose concentration (R2 = 0.44, P < 0.001), and tended to be greater in those on multiple daily insulin injections (MDI) vs continuous subcutaneous insulin infusion (CSII) (-98 ± 15 vs -65 ± 7 mg/dL, P = 0.05). No other collected variables appeared to predict the change in glucose including age, weight, height, body mass index, disease duration, daily insulin dose, HbA1c , or sex.Youth with T1D have variable glycemic responses to prolonged aerobic exercise, but this variability is partially explained by their pre-exercise blood glucose levels. When no implementation strategies are in place to limit the drop in glycemia, the incidence of exercise-associated hypoglycemia is ~44% and having a high pre-exercise blood glucose concentration is only marginally protective.

    View details for DOI 10.1111/pedi.12799

    View details for PubMedID 30467929

  • The Accuracy of Continuous Glucose Monitoring and Flash Glucose Monitoring During Aerobic Exercise in Type 1 Diabetes. Journal of diabetes science and technology Zaharieva, D. P., Riddell, M. C., Henske, J. 2019; 13 (1): 140-141

    View details for DOI 10.1177/1932296818804550

    View details for PubMedID 30295040

    View details for PubMedCentralID PMC6313274

  • Accuracy of Wrist-Worn Activity Monitors During Common Daily Physical Activities and Types of Structured Exercise: Evaluation Study. JMIR mHealth and uHealth Reddy, R. K., Pooni, R., Zaharieva, D. P., Senf, B., El Youssef, J., Dassau, E., Doyle Iii, F. J., Clements, M. A., Rickels, M. R., Patton, S. R., Castle, J. R., Riddell, M. C., Jacobs, P. G. 2018; 6 (12): e10338

    Abstract

    Wrist-worn activity monitors are often used to monitor heart rate (HR) and energy expenditure (EE) in a variety of settings including more recently in medical applications. The use of real-time physiological signals to inform medical systems including drug delivery systems and decision support systems will depend on the accuracy of the signals being measured, including accuracy of HR and EE. Prior studies assessed accuracy of wearables only during steady-state aerobic exercise.The objective of this study was to validate the accuracy of both HR and EE for 2 common wrist-worn devices during a variety of dynamic activities that represent various physical activities associated with daily living including structured exercise.We assessed the accuracy of both HR and EE for two common wrist-worn devices (Fitbit Charge 2 and Garmin vívosmart HR+) during dynamic activities. Over a 2-day period, 20 healthy adults (age: mean 27.5 [SD 6.0] years; body mass index: mean 22.5 [SD 2.3] kg/m2; 11 females) performed a maximal oxygen uptake test, free-weight resistance circuit, interval training session, and activities of daily living. Validity was assessed using an HR chest strap (Polar) and portable indirect calorimetry (Cosmed). Accuracy of the commercial wearables versus research-grade standards was determined using Bland-Altman analysis, correlational analysis, and error bias.Fitbit and Garmin were reasonably accurate at measuring HR but with an overall negative bias. There was more error observed during high-intensity activities when there was a lack of repetitive wrist motion and when the exercise mode indicator was not used. The Garmin estimated HR with a mean relative error (RE, %) of -3.3% (SD 16.7), whereas Fitbit estimated HR with an RE of -4.7% (SD 19.6) across all activities. The highest error was observed during high-intensity intervals on bike (Fitbit: -11.4% [SD 35.7]; Garmin: -14.3% [SD 20.5]) and lowest error during high-intensity intervals on treadmill (Fitbit: -1.7% [SD 11.5]; Garmin: -0.5% [SD 9.4]). Fitbit and Garmin EE estimates differed significantly, with Garmin having less negative bias (Fitbit: -19.3% [SD 28.9], Garmin: -1.6% [SD 30.6], P<.001) across all activities, and with both correlating poorly with indirect calorimetry measures.Two common wrist-worn devices (Fitbit Charge 2 and Garmin vívosmart HR+) show good HR accuracy, with a small negative bias, and reasonable EE estimates during low to moderate-intensity exercise and during a variety of common daily activities and exercise. Accuracy was compromised markedly when the activity indicator was not used on the watch or when activities involving less wrist motion such as cycle ergometry were done.

    View details for DOI 10.2196/10338

    View details for PubMedID 30530451

    View details for PubMedCentralID PMC6305876

  • A Pilot Study Validating Select Research-Grade and Consumer-Based Wearables Throughout a Range of Dynamic Exercise Intensities in Persons With and Without Type 1 Diabetes: A Novel Approach. Journal of diabetes science and technology Yavelberg, L., Zaharieva, D., Cinar, A., Riddell, M. C., Jamnik, V. 2018; 12 (3): 569-576

    Abstract

    The increasing popularity of wearable technology necessitates the evaluation of their accuracy to differentiate physical activity (PA) intensities. These devices may play an integral role in customizing PA interventions for primary prevention and secondary management of chronic diseases. For example, in persons with type 1 diabetes (T1D), PA greatly affects glucose concentrations depending on the intensity, mode (ie, aerobic, anaerobic, mixed), and duration. This variability in glucose responses underscores the importance of implementing dependable wearable technology in emerging avenues such as artificial pancreas systems.Participants completed three 40-minute, dynamic non-steady-state exercise sessions, while outfitted with multiple research (Fitmate, Metria, Bioharness) and consumer (Garmin, Fitbit) grade wearables. The data were extracted according to the devices' maximum sensitivity (eg, breath by breath, beat to beat, or minute time stamps) and averaged into minute-by-minute data. The variables of interest, heart rate (HR), breathing frequency, and energy expenditure (EE), were compared to validated criterion measures.Compared to deriving EE by laboratory indirect calorimetry standard, the Metria activity patch overestimates EE during light-to-moderate PA intensities (L-MI) and moderate-to-vigorous PA intensities (M-VI) (mean ± SD) (0.28 ± 1.62 kilocalories· minute-1, P < .001, 0.64 ± 1.65 kilocalories· minute-1, P < .001, respectively). The Metria underestimates EE during vigorous-to-maximal PA intensity (V-MI) (-1.78 ± 2.77 kilocalories · minute-1, P < .001). Similarly, compared to Polar HR monitor, the Bioharness underestimates HR at L-MI (-1 ± 8 bpm, P < .001) and M-VI (5 ± 11 bpm, P < .001), respectively. A significant difference in EE was observed for the Garmin device, compared to the Fitmate ( P < .001) during continuous L-MI activity.Overall, our study demonstrates that current research-grade wearable technologies operate within a ~10% error for both HR and EE during a wide range of dynamic exercise intensities. This level of accuracy for emerging research-grade instruments is considered both clinically and practically acceptable for research-based or consumer use. In conclusion, research-grade wearable technology that uses EE kilocalories · minute-1 and HR reliably differentiates PA intensities.

    View details for DOI 10.1177/1932296817750401

    View details for PubMedID 29320885

    View details for PubMedCentralID PMC6154246

  • Insulin Management Strategies for Exercise in Diabetes. Canadian journal of diabetes Zaharieva, D. P., Riddell, M. C. 2017; 41 (5): 507-516

    Abstract

    There is no question that regular exercise can be beneficial and lead to improvements in overall cardiovascular health. However, for patients with diabetes, exercise can also lead to challenges in maintaining blood glucose balance, particularly if patients are prescribed insulin or certain oral hypoglycemic agents. Hypoglycemia is the most common adverse event associated with exercise and insulin therapy, and the fear of hypoglycemia is also the greatest barrier to exercise for many patients. With the appropriate insulin dose adjustments and, in some cases, carbohydrate supplementation, blood glucose levels can be better managed during exercise and in recovery. In general, insulin strategies that help facilitate weight loss with regular exercise and recommendations around exercise adjustments to prevent hypoglycemia and hyperglycemia are often not discussed with patients because the recommendations can be complex and may differ from one individual to the next. This is a review of the current published literature on insulin dose adjustments and starting-point strategies for patients with diabetes in preparation for safe exercise.

    View details for DOI 10.1016/j.jcjd.2017.07.004

    View details for PubMedID 28942788

  • The Effects of Basal Insulin Suspension at the Start of Exercise on Blood Glucose Levels During Continuous Versus Circuit-Based Exercise in Individuals with Type 1 Diabetes on Continuous Subcutaneous Insulin Infusion. Diabetes technology & therapeutics Zaharieva, D., Yavelberg, L., Jamnik, V., Cinar, A., Turksoy, K., Riddell, M. C. 2017; 19 (6): 370-378

    Abstract

    Exercise causes glycemic disturbances in individuals with type 1 diabetes (T1D). Continuous moderate-intensity aerobic exercise (CON) generally lowers blood glucose (BG) levels and often leads to hypoglycemia. In comparison, circuit-based exercise (CIRC) may attenuate the drop in BG. The goal of this study is to contrast the effects of basal insulin suspension at the onset of two different forms of exercise (CON vs. CIRC).Twelve individuals (six men and six women) with T1D on insulin pump therapy were recruited for the study. All participants completed a maximal aerobic fitness test and two 40-min exercise sessions, consisting of either continuous treadmill walking or a circuit workout. Basal insulin infusion was stopped at the onset of exercise and resumed in recovery. After providing an initial reference value, volunteers were blinded to their [BG] and were asked to estimate their levels during exercise.Oxygen consumption (47.5 ± 7.5 vs. 54.5 ± 13.5 mL·kg-1·min-1, P = 0.03) and heart rate (122 ± 20 vs. 144 ± 20 bpm, P = 0.003) were lower in CON vs. CIRC. Despite the lower workload, BG levels dropped more with CON vs. CIRC (delta BG = -3.8 ± 1.5 vs. -0.5 ± 3.0 mmol/L for CON vs. CIRC, respectively, P = 0.001). Participants were able to estimate their BG more accurately during CON (r = 0.83) vs. CIRC (r = 0.33) based on a regression analysis.Despite a lower intensity of exercise, with full basal insulin suspension at the start of exercise, CON results in a larger drop in BG vs. CIRC. These findings have implications for single hormone-based artificial pancreas development for exercise. While this study does not negate the importance of frequent capillary BG monitoring during exercise, it does suggest that if persons are knowledgeable about their pre-exercise BG levels, they can accurately perceive the changes in BG during CON, but not during CIRC.

    View details for DOI 10.1089/dia.2017.0010

    View details for PubMedID 28613947

    View details for PubMedCentralID PMC5510047

  • Effects of acute caffeine supplementation on reducing exercise-associated hypoglycaemia in individuals with Type 1 diabetes mellitus. Diabetic medicine : a journal of the British Diabetic Association Zaharieva, D. P., Miadovnik, L. A., Rowan, C. P., Gumieniak, R. J., Jamnik, V. K., Riddell, M. C. 2016; 33 (4): 488-96

    Abstract

    To determine the effects of acute caffeine ingestion on glycaemia during moderate to vigorous intensity aerobic exercise and in recovery in individuals with Type 1 diabetes.A total of 13 patients with Type 1 diabetes [eight women, five men: mean ± sd age 25.9 ± 8.8 years, BMI 71.9 ± 11.0 kg, maximal oxygen consumption 46.6 ± 12.7 ml/kg/min, body fat 19.9 ± 7.2%, duration of diabetes 14.4 ± 10.1 years and HbA1c 55 ± 8 mmol/mol (7.4 ± 0.8%)] were recruited. Participants ingested capsules that contained gelatin or pure caffeine (6.0 mg/kg body mass) and performed afternoon exercise for 45 min at 60% maximal oxygen consumption on two separate visits with only circulating basal insulin levels.The main finding was that a single caffeine dose attenuates the drop in glycaemia by 1.8 ± 2.8 mmol/l compared with placebo intake during exercise (P=0.056). Continuous glucose monitoring data, however, showed that caffeine was associated with elevated glycaemia at bedtime after exercise, compared with placebo, but lower glucose concentrations in the early morning the next day.Caffeine intake should be considered as another strategy that may modestly attenuate hypoglycaemia in individuals with Type 1 diabetes during exercise, but should be taken with precautionary measures as it may increase the risk of late-onset hypoglycaemia.

    View details for DOI 10.1111/dme.12857

    View details for PubMedID 26173655

  • Classification of Physical Activity: Information to Artificial Pancreas Control Systems in Real Time. Journal of diabetes science and technology Turksoy, K., Paulino, T. M., Zaharieva, D. P., Yavelberg, L., Jamnik, V., Riddell, M. C., Cinar, A. 2015; 9 (6): 1200-7

    Abstract

    Physical activity has a wide range of effects on glucose concentrations in type 1 diabetes (T1D) depending on the type (ie, aerobic, anaerobic, mixed) and duration of activity performed. This variability in glucose responses to physical activity makes the development of artificial pancreas (AP) systems challenging. Automatic detection of exercise type and intensity, and its classification as aerobic or anaerobic would provide valuable information to AP control algorithms. This can be achieved by using a multivariable AP approach where biometric variables are measured and reported to the AP at high frequency. We developed a classification system that identifies, in real time, the exercise intensity and its reliance on aerobic or anaerobic metabolism and tested this approach using clinical data collected from 5 persons with T1D and 3 individuals without T1D in a controlled laboratory setting using a variety of common types of physical activity. The classifier had an average sensitivity of 98.7% for physiological data collected over a range of exercise modalities and intensities in these subjects. The classifier will be added as a new module to the integrated multivariable adaptive AP system to enable the detection of aerobic and anaerobic exercise for enhancing the accuracy of insulin infusion strategies during and after exercise.

    View details for DOI 10.1177/1932296815609369

    View details for PubMedID 26443291

    View details for PubMedCentralID PMC4667299

  • Exercise and the Development of the Artificial Pancreas: One of the More Difficult Series of Hurdles. Journal of diabetes science and technology Riddell, M. C., Zaharieva, D. P., Yavelberg, L., Cinar, A., Jamnik, V. K. 2015; 9 (6): 1217-26

    Abstract

    Regular physical activity (PA) promotes numerous health benefits for people living with type 1 diabetes (T1D). However, PA also complicates blood glucose control. Factors affecting blood glucose fluctuations during PA include activity type, intensity and duration as well as the amount of insulin and food in the body at the time of the activity. To maintain equilibrium with blood glucose concentrations during PA, the rate of glucose appearance (Ra) to disappearance (Rd) in the bloodstream must be balanced. In nondiabetics, there is a rise in glucagon and a reduction in insulin release at the onset of mild to moderate aerobic PA. During intense aerobic -anaerobic work, insulin release first decreases and then rises rapidly in early recovery to offset a more dramatic increase in counterregulatory hormones and metabolites. An "exercise smart" artificial pancreas (AP) must be capable of sensing glucose and perhaps other physiological responses to various types and intensities of PA. The emergence of this new technology may benefit active persons with T1D who are prone to hypo and hyperglycemia.

    View details for DOI 10.1177/1932296815609370

    View details for PubMedID 26428933

    View details for PubMedCentralID PMC4667314

  • The "ups" and "downs" of a bike race in people with type 1 diabetes: dramatic differences in strategies and blood glucose responses in the Paris-to-Ancaster Spring Classic. Canadian journal of diabetes Yardley, J. E., Zaharieva, D. P., Jarvis, C., Riddell, M. C. 2015; 39 (2): 105-10

    Abstract

    Recommendations for insulin adjustments and carbohydrate intake exist for individuals with type 1 diabetes who are undertaking moderate exercise. Very few guidelines exist for athletes with type 1 diabetes who are competing in events of higher intensity or longer duration. This observational study reports the strategies adopted by 6 habitually active men with type 1 diabetes (glycated hemoglobin = 8.3%±2.0%) undertaking a relatively intense endurance cycling event.Participants wore continuous glucose monitoring (CGM) sensors for 24 hours before competition, while racing and overnight postrace. They were asked to eat their regular meals and snacks and make their usual insulin adjustments before, during and after competition. All food intake and insulin adjustments were recorded in detail.Participants used a variety of adjustments for exercise. Of 6 participants, 4 decreased their insulin dosages and all participants consumed carbohydrates during the race (mean = 87±57 g). In spite of these strategies, 3 of the 6 participants experienced mild to moderate hypoglycemia (not requiring assistance) during the event. Hyperglycemia was seen in all participants 3 hours postexercise. There were no incidents of nocturnal hypoglycemia.Individuals with type 1 diabetes can compete in intensive long-distance athletic events using a variety of nutrition- and insulin-adjustment strategies. In addition to finely tuned insulin adjustments and increased carbohydrate intake, vigilance will always be required to maintain some semblance of glycemic control during events of extended duration.

    View details for DOI 10.1016/j.jcjd.2014.09.003

    View details for PubMedID 25492557

  • Prevention of exercise-associated dysglycemia: a case study-based approach. Diabetes spectrum : a publication of the American Diabetes Association Zaharieva, D. P., Riddell, M. C. 2015; 28 (1): 55-62

    View details for DOI 10.2337/diaspect.28.1.55

    View details for PubMedID 25717279

    View details for PubMedCentralID PMC4334080

  • Effects of selective and non-selective glucocorticoid receptor II antagonists on rapid-onset diabetes in young rats. PloS one Beaudry, J. L., Dunford, E. C., Teich, T., Zaharieva, D., Hunt, H., Belanoff, J. K., Riddell, M. C. 2014; 9 (3): e91248

    Abstract

    The blockade of glucocorticoid (GC) action through antagonism of the glucocorticoid receptor II (GRII) has been used to minimize the undesirable effects of chronically elevated GC levels. Mifepristone (RU486) is known to competitively block GRII action, but not exclusively, as it antagonizes the progesterone receptor. A number of new selective GRII antagonists have been developed, but limited testing has been completed in animal models of overt type 2 diabetes mellitus. Therefore, two selective GRII antagonists (C113176 and C108297) were tested to determine their effects in our model of GC-induced rapid-onset diabetes (ROD). Male Sprague-Dawley rats (∼ six weeks of age) were placed on a high-fat diet (60%), surgically implanted with pellets containing corticosterone (CORT) or wax (control) and divided into five treatment groups. Each group was treated with either a GRII antagonist or vehicle for 14 days after surgery: CORT pellets (400 mg/rat) + antagonists (80 mg/kg/day); CORT pellets + drug vehicle; and wax pellets (control) + drug vehicle. After 10 days of CORT treatment, body mass gain was increased with RU486 (by ∼20% from baseline) and maintained with C113176 administration, whereas rats given C108297 had similar body mass loss (∼15%) to ROD animals. Fasting glycemia was elevated in the ROD animals (>20 mM), normalized completely in animals treated with RU486 (6.2±0.1 mM, p<0.05) and improved in animals treated with C108297 and C113176 (14.0±1.6 and 8.8±1.6 mM, p<0.05 respectively). Glucose intolerance was normalized with RU486 treatment, whereas acute insulin response was improved with RU486 and C113176 treatment. Also, peripheral insulin resistance was attenuated with C113176 treatment along with improved levels of β-cell function while C108297 antagonism only provided modest improvements. In summary, C113176 is an effective agent that minimized some GC-induced detrimental metabolic effects and may provide an alternative to the effective, but non-selective, GRII antagonist RU486.

    View details for DOI 10.1371/journal.pone.0091248

    View details for PubMedID 24642683

    View details for PubMedCentralID PMC3958344

  • Caffeine and glucose homeostasis during rest and exercise in diabetes mellitus. Applied physiology, nutrition, and metabolism = Physiologie appliquee, nutrition et metabolisme Zaharieva, D. P., Riddell, M. C. 2013; 38 (8): 813-22

    Abstract

    Caffeine is a substance that has been used in our society for generations, primarily for its effects on the central nervous system that causes wakefulness. Caffeine supplementation has become increasingly more popular as an ergogenic aid for athletes and considerable scientific evidence supports its effectiveness. Because of their potential to alter energy metabolism, the effects of coffee and caffeine on glucose metabolism in diabetes have also been studied both epidemiologically and experimentally. Predominantly targeting the adenosine receptors, caffeine causes alterations in glucose homeostasis by decreasing glucose uptake into skeletal muscle, thereby causing elevations in blood glucose concentration. Caffeine intake has also been proposed to increase symptomatic warning signs of hypoglycemia in patients with type 1 diabetes and elevate blood glucose levels in patients with type 2 diabetes. Other effects include potential increases in glucose counterregulatory hormones such as epinephrine, which can also decrease peripheral glucose disposal. Despite these established physiological effects, increased coffee intake has been associated with reduced risk of developing type 2 diabetes in large-scale epidemiological studies. This review paper highlights the known effects of caffeine on glucose homeostasis and diabetes metabolism during rest and exercise.

    View details for DOI 10.1139/apnm-2012-0471

    View details for PubMedID 23855268