Insulin Insulin Insulin (from Latin "insula", island) is a peptide hormone produced by beta cells of the pancreatic islets; it is considered to be the main anabolic hormone of the body. It regulates the metabolism of carbohydrates, fats and protein by promoting the absorption of carbohydrates, especially glucose from the blood into liver, fat and skeletal muscle cells. In these tissues the absorbed glucose is converted into either glycogen via glycogenesis or fats (triglycerides) via lipogenesis, or, in the case of the liver, into both. Glucose production and secretion by the liver is strongly inhibited by high concentrations of insulin in
Glycogen storage disease type 0 liver provides a steady source of glucose from glycogen breakdown (or glycogenolysis). With prolonged fasting, glucose is generated in the liver from noncarbohydrate precursors through gluconeogenesis. Such precursors include alanine (derived from the breakdown of proteins in skeletal muscle) and glycerol (derived from the breakdown of triacylglycerols in fat cells). In patients with glycogen-storage disease type 0, fasting hypoglycemia occurs within a few hours after a meal because of the limited stores of hepatic glycogen and inadequate gluconeogenesis to maintain normoglycemia. Feeding characteristically results in postprandial hyperglycemia and glucosuria, in addition to increased blood lactate levels, because glycogen synthesis is