Validation in adult Black and White women of the ISS model for estimating insulin sensitivity and beta-cell function from mixed-meal tests

The Insulin Sensitivity and Secretion (ISS) differential equation model has been previously shown to provide simultaneous estimates of insulin sensitivity (SI) and beta-cell function (BCF) during an oral glucose tolerance test. Using the Federal Women's Study, we adapted the ISS model to fit glucose and insulin dynamics and estimate SI and BCF during mixed-meal tests (MMTs). Our goal was to develop an effective, straightforward, and reliable tool that would be simpler to use than currently available approaches that require technically challenging deconvolution methods to assess BCF. The ISS model for mixed-meal tests strongly correlated with oral glucose tolerance tests and gold-standard estimates from intravenous glucose tolerance tests and was reliable when using a shortened 2-h MMT protocol. The ISS model is versatile, publicly available, and expands the toolbox for assessing postprandial glucose-insulin homeostasis.NEW & NOTEWORTHY We have previously validated a differential equation model (the ISS model) to determine insulin sensitivity and beta-cell function from oral glucose tolerance tests. The ISS model is simpler to use and requires less data than other current models. We have now extended this model of glucose-insulin metabolism for use with mixed-meal tolerance tests; MMTs may be preferred because they are more physiological and closer to what people eat in daily life.