American Diabetes Association
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Time to Peak Glucose and Peak C-Peptide During the Progression to Type 1 Diabetes in the Diabetes Prevention Trial and TrialNet Cohorts

Version 3 2021-08-06, 16:23
Version 2 2021-08-06, 16:23
Version 1 2021-08-06, 16:22
posted on 2021-08-06, 16:23 authored by Michael G Voss, David D Cuthbertson, Mario M Cleves, Ping Xu, Carmella Evans-Molina, Jerry P Palmer, Maria J. Redondo, Andrea K. Steck, Markus Lundgren, Helena Larsson, Wayne V Moore, Mark A. Atkinson, Jay Sosenko, Heba M Ismail, DPT-1 and TrialNet Study Groups
Objective: To assess the progression of type 1 diabetes using time to peak glucose or C-peptide during oral glucose tolerance tests (OGTTs) in autoantibody positive (Ab+) relatives of people with type 1 diabetes.

Methods: We examined 2-hour OGTTs of participants in the Diabetes Prevention Trial Type 1 (DPT-1) and TrialNet Pathway to Prevention (PTP) studies. We included 706 DPT-1 participants (Mean±SD age: 13.84±9.53 years; BMI-Z-Score: 0.33±1.07; 56.1% male) and 3,720 PTP participants (age: 16.01±12.33 Years, BMI-Z-Score 0.66±1.3; 49.7% male). Log-rank testing and Cox regression analyses with adjustments (age, sex, race, BMI Z-Score, HOMA-IR and peak Glucose/C-peptide levels, respectively) were performed.

Results: In each of DPT-1 and PTP, higher 5-year diabetes progression risk was seen in those with time to peak glucose >30 min and time to peak C-peptide >60 min (p<0.001 for all groups), before and after adjustments. In models examining strength of association with diabetes development, associations were greater for time to peak C-peptide versus peak C-peptide value (DPT-1: X2 = 25.76 vs. X2 = 8.62 and PTP: X2 = 149.19 vs. X2 = 79.98; all p<0.001). Changes in the percentage of individuals with delayed glucose and/or C-peptide peaks were noted over time.

Conclusions: In two independent at risk populations, we show that those with delayed OGTT peak times for glucose or C-peptide are at higher risk of diabetes development within 5 years, independent of peak levels. Moreover, time to peak C-peptide appears more predictive than the peak level, suggesting its potential use as a specific biomarker for diabetes progression.


We acknowledge the support of the Type 1 Diabetes TrialNet Study Group, which identified study participants and provided samples and follow-up data for this study. The Type 1 Diabetes TrialNet Study Group is a clinical trials network funded by the National Institutes of Health (NIH) through the National Institute of Diabetes and Digestive and Kidney Diseases, the National Institute of Allergy and Infectious Diseases, and The Eunice Kennedy Shriver National Institute of Child Health and Human Development, through the cooperative agreements U01 DK061010, U01 DK061034, U01 DK061042, U01 DK061058, U01 DK085453, U01 DK085461, U01 DK085465, U01 DK085466, U01 DK085476, U01 DK085499, U01 DK085504, U01 DK085509, U01 DK103180, U01 DK103153, U01 DK103266, U01 DK103282, U01 DK106984, U01 DK106994, U01 DK107013, U01 DK107014, UC4 DK106993, UC4 DK11700901, U01 DK 106693-02, and the JDRF. The contents of this article are solely the responsibility of the authors and do not necessarily represent the official views of the NIH or the JDRF. This work was also made possible with support from Grant Numbers, KL2TR002530 (A Carroll, PI), and UL1TR002529 (A. Shekhar, PI) from the National Institutes of Health, National Center for Advancing Translational Sciences, Clinical and Translational Sciences Award.


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