somatostatin (growth hormone inhibiting hormone; GHIH) A hormone, secreted by the hypothalamus, that inhibits the release of growth hormone from the anterior pituitary gland (see release-inhibiting hormone). The secretion of somatostatin is stimulated by various factors, including very high blood glucose levels, which result from the effect that growth hormone has on glucose metabolism. It is also produced by the δ (or D) cells of the islets of Langerhans in the pancreas, where it can inhibit the release of glucagon and insulin.

somatostatin (growth-hormone inhibiting hormone, GHIH) (soh-mă-toh-stay-tin) n. a hormone, produced by the hypothalamus and some extraneural tissues, including the gastrointestinal tract and the pancreas (see D cells), that inhibits the secretion of many hormones, including growth hormone (somatotrophin), insulin, and glucagon. s. analogue a drug, such as lanreotide or octreotide, used to treat symptoms caused by neuroendocrine tumours, including carcinoid syndrome.