A model for assessing insulin secretion and its control under free-living conditions.

A well-established approach for the estimation of insulin secretion in vivo is based on the measurement of plasma C-peptide. C-peptide is secreted by pancreatic -cells in equimolar amounts with insulin, but unlike insulin, C-peptide is not extracted by the liver and has a constant peripheral clearance. Thus, the systemic (venous) appearance of C-peptide equals the pancreatic release of insulin. The C-peptide systemic appearance can be calculated by deconvolution from the plasma C-peptide concentrations and a kinetic model of C-peptide distribution (1). This method has been used to evaluate 24-h profiles of insulin secretion (2) and the -cell dose-response curve (3). We developed a model for assessing the 24-h profile of insulin secretion and its control by glucose, simultaneously. To date, the model has been tested in lean and obese nondiabetic subjects.