Impact of age on C-peptide after diagnosis. A: Model-based estimates of average slopes of C-peptide area under the curve (AUC) over time according to age quartiles (age-groups 7.7–12.3 years, 12.4–14.7 years, 14.8–21.2 years, and 21.4–46.1 years). Data from 191 TrialNet clinical trial participants. Reprinted with permission from Greenbaum et al. (63). B: Proportion of participants with detectable (≥0.017 nmol/L) nonfasting C-peptide according to age at diagnosis and duration of type 1 diabetes. White bars, those diagnosed at age ≤18 years; black bars, those diagnosed at age >18 years. Data from the T1D Exchange residual insulin study. Reprinted with permission from Davis et al. (64).