589-P: Effect of Oral Insulin (OI) on Combined Glucose and C-Peptide Endpoints in Individuals at High-Risk for Type 1 Diabetes (T1D)

The TrialNet OI prevention trial (TN07) with T1D as an endpoint showed no effect. However, in a smaller trial run in parallel with TN07 (termed secondary stratum 1), in which all participants had low first-phase insulin release, a statistically significant delay in T1D onset was found. Since trials with T1D as an endpoint take years to complete, we aimed to determine if combination C-peptide and glucose markers could identify a therapeutic benefit after 12 months of OI in this high-risk population. All participants were at-risk relatives with multiple autoantibodies including mIAA and normal glucose tolerance (n=40 with full data). The Figure shows changes in glucose and C-peptide response curves and their centroids (central points). Glucose rose and C-peptide declined in the placebo group compared to a minimal glucose rise with an increase of C-peptide in the OI group. Change from baseline to 1 year in the centroid ratio (C-peptide/glucose) differed significantly between groups (p=0.037 after adjustments for age, BMI, and baseline C-peptide and glucose). The AUC C-peptide/AUC glucose ratio and Index60 did not differ (both p=0.108). In conclusion, the findings support a positive effect of OI on combined glucose and C-peptide endpoints in high-risk individuals. These measures appear to detect differences in a shorter time than the standard T1D endpoint. Disclosure L. M. Jacobsen: None. M. A. Atkinson: None. J. Krischer: None. D. Schatz: Advisory Panel; Self; Abbott, Medtronic. J. Sosenko: None. D. D. Cuthbertson: None. E. K. Sims: None. H. M. Ismail: None. L. Dimeglio: Advisory Panel; Self; MannKind Corporation. T. M. Triolo: None. M. J. Redondo: Advisory Panel; Self; Provention Bio, Inc. M. Lundgren: None. P. Gottlieb: Advisory Panel; Self; Janssen Research & Development, LLC, Tolerion, Inc., Viacyte, Inc., Other Relationship; Self; ImmunoMolecular Therapeutics, Inc., Research Support; Self; Caladrius Biosciences, Inc., Immune Tolerance Network, Mercia Pharma Inc., National Institute of Diabetes and Digestive and Kidney Diseases, Precigen, Inc., Tolerion, Inc.