Insulin

A hormone produced by the pancreas that regulates glucose levels in the blood. It is normally produced in response to raised glucose levels following a meal and promotes glucose absorption into the liver and muscle cells (where it is converted into energy). Insulin thus prevents a build-up of glucose and ensures that tissues have sufficient amounts of glucose. Failure of insulin production results in diabetes mellitus. An insulinoma is a rare tumour that causes excessive production of insulin and consequent attacks of hypoglycaemia. Insulin replacement, self-administered by injection or through an infusion pump (see pump, insulin), is used in the treatment of diabetes mellitus. Insulin cannot be taken orally because it is destroyed by stomach acid. Preparations are produced from pig or ox pancreas or, more commonly, by genetic engineering. This treatment prevents excessively high glucose levels in blood ( hyperglycaemia) and ketosis (a buildup of certain acids in the blood), which, in severe cases, may cause coma. Too high a dose of insulin will cause hypoglycaemia, which can be relieved by consuming food or a sugary drink. Severe hypoglycaemia may cause coma, for which emergency treatment with an injection of glucose or glucagon (a hormone that opposes the effects of insulin) is necessary.