Gastric Inhibitory Peptide (GIP), also known as gastric inhibitory polypeptide, or glucose-dependent insulinotropic polypeptide, is a 42-amino-acid peptide hormone synthesized in and secreted from K cells in the intestinal epithelium. GIP secretion is primarily regulated by nutrients, especially fat. GIP exhibits potent incretin activity in rodents and human subjects. The primary action of GIP is the stimulation of glucose-dependent insulin secretion. GIP may also play a role in adipocyte biology.