20-OR: Loss of Characteristic ß-Cell Function in Autoantibody-Positive (Ab+) Individuals during the Progression to Type 1 Diabetes (T1D)

We used correlations of C-peptide secretion between follow-up time points (autocorrelation) of Ab+ relatives in the TrialNet Pathway to Prevention study to assess the loss of characteristic β-cell function during progression to T1D. Measures of β-cell function: AUC C-peptide; C-peptide Index (30-0 min C-peptide)/(30-0 min glucose); and Index60 (composite of glucose and C-peptide during first 60 minutes of OGTT)] were assessed (table 1). Spearman correlations of AUC C-peptide from baseline to pre-diagnosis (6 months before) OGTTs of progressors (Pro; Age=8.7±3.6 yrs; n=182) were lower than correlations of AUC C-peptide from baseline to last OGTTs of non-progressors (NPro; Age=9.6±3.8 yrs; n=3,137; p<0.001 for all). Among Pro, correlations of AUC C-peptide from baseline to diagnosis OGTTs were considerably lower than correlations of AUC C-peptide from baseline to pre-diagnosis OGTTs (p=<0.001 for all). In conclusion, the lower C-peptide autocorrelation from baseline to last OGTTs of Pro compared to NPro indicates that β-cell function is already appreciably altered 6 months before diagnosis. Among Pro, the substantial decline of C-peptide autocorrelation from 6 months before diagnosis to diagnosis suggests a marked loss of β-cell function in that interval. Autocorrelation offers another approach for providing insight into β-cell compromise.

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