What is the function of glucose-dependent insulinotropic polypeptide (GIP)?

• A. Stimulates glucagon secretion
• B. Stimulates insulin secretion
• C. Suppresses appetite
• D. Inhibits gastric emptying

Answer: (B)

GIP is an incretin hormone released by K cells in the small intestine in response to nutrients, especially glucose and fat, and its primary function is to boost insulin secretion from pancreatic beta cells in a glucose-dependent manner after a meal. This means insulin is released when blood glucose is rising due to nutrient intake, helping to regulate postprandial glucose without causing hypoglycemia. While GIP can influence other hormones in some contexts, its defining action is stimulating insulin release, making it the best answer. In contrast, substantial suppression of appetite or inhibition of gastric emptying are more closely linked to GLP-1, and although GIP can affect glucagon secretion under certain conditions, the hallmark role is enhancing insulin secretion.