Glucagon (None)

Glucagon is a **peptide hormone** produced mainly by the **alpha cells of the pancreas** and acts as a critical counter-regulator to insulin in the maintenance of blood glucose homeostasis[3][5][1]. When blood sugar falls (hypoglycemia), glucagon is released, stimulating **glycogenolysis** (breakdown of glycogen into glucose) and **gluconeogenesis** (creation of glucose from amino acids) in the liver, raising blood glucose[3][5][1]. It also inhibits glycolysis and fatty acid synthesis while promoting lipolysis in adipose tissue, releasing fatty acids for metabolic use. Therapeutically, glucagon is used as a drug (for example, by emergency injection) to treat severe hypoglycemia, especially in people with diabetes, and as a diagnostic aid to temporarily relax the gastrointestinal tract during imaging procedures[4][7][6]. Safety concerns mainly include nausea, vomiting, and hyperglycemia; it may not be effective if liver glycogen is depleted. Glucagon works by binding its G protein-coupled receptor on hepatocytes and other target cells, activating intracellular signaling cascades that result in rapid glucose release into the bloodstream[1][3][7].

Other names

pancreatic glucagonGCG

Drugs (e.g., injectable glucagon) act as **agonists of the glucagon receptor**, stimulating the liver to release glucose into the bloodstream via activation of hepatic glucagon receptors, which stimulates glycogenolysis and gluconeogenesis[3][7][4] Other agents (not clinically established) may target the glucagon receptor for antagonism in diabetes research