title: A mathematical model of the oral glucose tolerance test illustrating the effects of the incretins.
abstract: Despite important empirical findings, current models of the oral glucose tolerance test (OGTT) do not incorporate the essential contributions of the incretin hormones, glucagon-like peptide-1 and glucose-dependent insulinotropic peptide, to glucose-stimulated insulin secretion. In order to address this deficiency, a model was, therefore, developed in which the incretins, as well as a term reflecting net hepatic glucose balance, were included. Equations modeling the changes in incretins, hepatic glucose balance, insulin and glucose were used to simulate the responses to 50 and 100 g oral glucose loads under normal conditions. The model successfully captures main trends in mean data from the literature using a simple 'lumped-parameter,' single-compartment approach in which the majority of the parameters were matched to known clinical data. The accuracy of the model and its applicability to understanding fundamental mechanisms was further assessed using a variety of glycemic and insulinemic challenges beyond those which the model was originally created to encompass, including hyper- and hypoinsulinemia, changes in insulin sensitivity, and the insulin infusion-modified intravenous glucose tolerance test.
authors: Department of Physiology, University of Toronto, Toronto, Canada.
authors: Patricia L
authors: PL
authors: Brubaker
authors: Elan L
authors: EL
authors: Ohayon
authors: Lisa M
authors: LM
authors: D'Alessandro
authors: Kenneth H
authors: KH
authors: Norwich
mesh_terms: D000284:Administration, Oral; D005749:Gastric Inhibitory Polypeptide / Q000502:physiology*; D052216:Glucagon-Like Peptide 1 / Q000502:physiology*; D005947:Glucose / Q000378:metabolism*; D018149:Glucose Intolerance; D005951:Glucose Tolerance Test; D006728:Hormones / Q000502:physiology; D006801:Humans; D007328:Insulin / Q000502:physiology*; D008962:Models, Theoretical
chemical_list: D006728:Hormones; D007328:Insulin; D005749:Gastric Inhibitory Polypeptide; D052216:Glucagon-Like Peptide 1; D005947:Glucose