Ismail HM, Becker DJ, Libman I, et al. - Researchers investigated the predictive value of the timing of the C-peptide response during an oral glucose tolerance test (OGTT) in relatives of type 1 diabetes (T1D) patients for disease onset. From 670 relatives participating in the Diabetes Prevention Trial-Type 1, they assessed baseline 2-hr OGTTs (age: 13.8±9.6 years; BMI-z: 0.3±1.1; 56% male) using univariate regression models. With lower early C-peptide responses (30-0 min), and higher late C-peptide responses (120-60 min), an increase in T1D risk was observed. This suggests the value of lower early and higher late C-peptide responses as indicators of increased T1D risk.