GLP-1 receptor agonist
A GLP-1 receptor agonist is a drug that imitates a natural gut hormone your body releases after eating, the one that tells the pancreas "food is coming, get insulin ready." By copying this signal, the drug helps lower blood sugar in type 2 diabetes and, as a bonus that has made these drugs famous, blunts appetite and promotes weight loss.
GLP-1 (glucagon-like peptide-1) is an incretin hormone. These agonists activate the GLP-1 receptor, a GPCR, and produce several glucose-lowering effects: they stimulate insulin release but only when blood glucose is high (glucose-dependent), suppress the counter-regulatory hormone glucagon, slow stomach emptying so glucose enters more gradually, and act on the brain to reduce hunger. Because insulin release is glucose-dependent, used alone they rarely cause hypoglycaemia. Examples include semaglutide, liraglutide, and dulaglutide; most are injected, though an oral semaglutide exists.
Beyond glucose control, several agents in this class have shown cardiovascular and kidney benefits in trials and produce substantial weight loss, broadening their use into obesity management. The most common adverse effects are gastrointestinal, especially nausea, vomiting, and diarrhoea, usually worst at the start and eased by slow dose escalation. Rarer concerns include pancreatitis and gallbladder disease, and they are avoided in people with a personal or family history of medullary thyroid carcinoma.
Because GLP-1 receptor agonists stimulate insulin only when glucose is elevated, their hypoglycaemia risk is low when used alone, but it rises if combined with insulin or a sulfonylurea, whose doses may need reduction.