Composite Scores Using Fasting and Stimulated C-Peptide Are Equivalent and Can Track Beta-Cell Function in New-Onset Type 1 Diabetes

Composite scores using fasting samples have been developed to routinely monitor beta cell mass after islet transplantation in type 1 diabetes (T1D). They may also have utility in new onset or T1D prevention trials as an alternative to mixed meal tolerance tests measuring AUC C-peptide. We examined if a composite score using stimulated C-peptide was equivalent to fasting C-peptide in estimating beta cell mass in new onset T1D and reflected changes in AUC C-peptide over time. BETA-2 (fasting C-peptide, glucose, insulin dose, HbA1c) and BETA-2stim (using C-peptide AUC) were calculated in 1312 individuals from the TOMI dataset (median (IQR) age 16y (12, 24); 42% F). The dataset comprises 3200 participants within 100 days of diagnosis across 22 studies. Studies meeting their primary end point were deemed positive. BETA-2 and BETA-2stim were strongly correlated (R2=0.96, p<0.0001) and showed good agreement using Bland-Altman plots. Both BETA-2 and BETA-2stim showed changes over time which mirrored those for AUC C-peptide, but both composite scores showed differences between active and control participants in positive studies by 3 months while differences in AUC C-peptide were not seen until 6 months (Fig1). Composite scores using fasting C-peptide may provide a simple, sensitive and practical tool to monitor beta cell mass without complex stimulation tests in new onset diabetes. Disclosure A.Carr: None. K.S.Collins: None. S.Karpen: None. E.Atabakhsh: None. A.Lam: None. P.Taylor: None. C.Dayan: Advisory Panel; AstraZeneca, Consultant; Provention Bio, Sanofi, Avotres Inc., Other Relationship; Dompé, Merck & Co., Inc. P.A.Senior: Advisory Panel; Novo Nordisk Canada Inc., Consultant; Novo Nordisk Canada Inc., Bayer Inc., Viatris Inc., Vertex Pharmaceuticals Incorporated, ViaCyte, Inc., Insulet Corporation.