Standardized Mixed-Meal Tolerance and Arginine Stimulation Tests Provide Reproducible and Complementary Measures ofb-cell Function: Results From the Foundation for the National Institutes of Health Biomarkers Consortium Investigative Series

Standardized, reproducible, and feasible quantification ofb-cell function (BCF) is necessary for the evaluation of interventions to improve insulin secretion and important for comparison across studies. We therefore characterized the re-sponses to, and reproducibility of, standardized methods of in vivo BCF across different glucose tolerance states. Reproducibility for the AST was very good, with ICC values >0.8 across all variables and populations.