Background – The incretin hormones such as GIP and GLP-1 are released from endocrine cells in the intestinal mucosa after ingestion of carbohydrates and enhance postprandial insulin release from the pancreatic beta cells. The released insulin stimulates glucose uptake in skeletal muscles and adipocytes, and the enhancement of the glucose disappearance rate from blood (glucose clearance: GC) is promoted by the facilitative subcellular redistribution of the glucose transpoter isoform (GLUT4) from an intracellular compartment to the plasma membrane. The ability to stimulate incretin hormone secretion differs among the various types of carbohydrates.
Objective – To clarify the relationship between the insulin release (AUC of plasma insulin concentration: AUCINS) and GC after intravenous and oral administration of glucose, and to examine whether the relationship can be used to predict the intestinal glucose absorption rate after intakes of various types of carbohydrates such as sucrose.
Design – The glucose was intravenously infused into male Wistar rats. The oral glucose tolerance test (OGTT) was also performed using Trelan-G. Sucrose was administered orally. The alterations of plasma glucose and insulin concentrations were measured, and the simple kinetic model was used to determine their GC.
Outcomes and Conclusions – The values of AUCINS and GC after oral administration of glucose were greater than those after intravenous infusion of the same amount of glucose. There was a strong positive correlation between AUCINS and GC after either intravenous or oral administration of glucose. It was clarified that the intestinal glucose absorption rate after intake of sucrose could be predicted from the relationship between AUCINS and GC.