The Pathological Evolution of Glucose Response Curves During the Progression to Type 1 Diabetes in the TrialNet Pathway to Prevention Study
figureposted on 08.09.2020 by Heba M. Ismail, Mario A. Cleves, Ping Xu, Ingrid M. Libman, Dorothy J. Becker, Jennifer B. Marks, Jay S. Skyler, Jerry P. Palmer, Jay M. Sosenko, Type 1 Diabetes TrialNet Study Group
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Objective: Glucose response curves (GRCs) during oral glucose tolerance tests (OGTTs) are predictive of type 1 diabetes. We performed a longitudinal analysis in pancreatic autoantibody positive (Ab+) individuals to assess: 1) characteristic GRC changes during progression to type 1 diabetes, and 2) GRC changes in relation to β-cell function changes and to combined glucose and C-peptide response curve (GCRC) changes. Research Design and Methods: Among Ab+ individuals with serial OGTTs in the TrialNet Pathway to Prevention study, GRC changes from first to last OGTTs were compared between progressors (n=298) to type 1 diabetes and non-progressors (n=2216). GRC changes from last before diagnosis to diagnostic OGTTs were studied in progressors. Results: GRCs changed more frequently from Biphasic (2 peaks) to Monophasic (1 peak) GRCs between first and last OGTTs in progressors than in non-progressors [75.4% vs. 51.0%; p<0.001]. In contrast, progressors changed less frequently from Monophasic to Biphasic than non-progressors [12.6% vs. 30.6%; p <0.001]. Monotonic (continuous increase) GRCs were present in 47.7% of progressors at diagnosis. The early (30-0 min) C-peptide response decreased in progressors changing from Biphasic to Monophasic between first and last OGTTs (p<0.001) and from Monophasic to Monotonic between last and diagnostic OGTTs (p<0.001). Conversely, the early C-peptide response increased among non-progressors changing from Monophasic to Biphasic (p<0.001). Changes in GRCs were related to changes in GCRCs. Conclusions: Characteristic GRC changes, Biphasic to Monophasic to Monotonic, occur during the progression to type 1 diabetes. These GRC changes correspond to decreasing β-cell function.