Regulation of glucose metabolism by incretins: implications for treatment of type 2 diabetes

Gastrointestinal hormones that potentiate insulin secretion from pancreatic β-cells are called incretins. Glucose-dependent insulinotropic polypeptide/gastric inhibitory polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) are the major incretins. Incretin-mediated stimulation of insulin secretion (incretin effect) plays an important role in lowering postprandial blood-glucose levels. Incretin effect is reduced under diabetic condition. Several mechanisms have been reported for the reduction of incretin effect. Incretin-related drugs are used worldwide for the treatment of type 2 diabetes. In addition, several new incretin-related drugs have been developed and are expected to be available in clinical practice.