Effect of Oral Insulin on Early Combined Glucose and C‐Peptide Endpoints in Individuals at High‐Risk for Type 1 Diabetes.

Background: The TrialNet Oral Insulin (OI) prevention trial showed no overall treatment effect, using the diagnosis of type 1 diabetes as an endpoint. A significant delay in onset was only found in a high‐risk stratum (termed secondary stratum 1) of participants with low first‐phase insulin release (FPIR). Methods: Since trials with an endpoint of type 1 diabetes take years to complete, in this post hoc analysis, we assessed whether a novel combination of glucose and C‐peptide markers could identify a therapeutic benefit after 1 year of follow‐up (trial participants followed for a median 2.7 years). Results: Participants were relatives with multiple islet autoantibodies and low FPIR (n = 40). Glucose rose, and C‐peptide declined in the placebo group, whereas glucose rose minimally, and C‐peptide increased in the OI group. When glucose and C‐peptide were plotted on two‐dimensional grids using 30–120‐min oral glucose tolerance test (OGTT) time points, changes in ratios of their central points (centroid ratio) differed between groups (p = 0.037 adjusted for age, BMI, and baseline C‐peptide and glucose). Conclusions: These findings support a favorable early effect of OI on combined glucose and C‐peptide endpoints in high‐risk individuals, indicating metabolic benefit. With further study, these measures may allow for shorter trials compared to the standard endpoint of type 1 diabetes diagnosis. [ABSTRACT FROM AUTHOR]