Insulin release is by:

Ans: b (Exocytosis) Ref: Vasudevan, 4th ed, p.107Insulin is secreted by exocytosis.Secretion of insulin:The insulin is packed in to granules in the Golgi apparatus.The insulin molecules associate into a hexamer with two zinc ions and one calcium ion. The contents of granules are released by exocytosis; both insulin and C-peptide are released into circulation.Degradation of insulin:Insulin is rapidly degraded in liver. Plasma half life is less than 5 minutes.An insulin specific protease (insulinase) and a hepatic glutathione- insulin- trans hydrogenase are involved in degradation of insulin.Note:Glucose is the major stimulant of insulin secretion.Pro insulin has about one third biological activity of insulin.