insulin definition biology
insulin. n. 1. (Biology) a protein hormone, secreted in the pancreas by the islets of Langerhans, that controls the concentration of glucose in the blood. Insulin deficiency results in diabetes mellitus. [C20: from New Latin insula islet (of the pancreas) + -in]. (ËÉªn sÉ lÉªn, ËÉªns yÉ-). n.