What an incretin does
Incretins are hormones your small intestine releases within minutes of eating. Their headline job is the “incretin effect”: they prompt the pancreas to release insulin in response to a meal, which is why food raises blood sugar less than the same amount of glucose given intravenously. The two incretins that matter most are GLP-1 (glucagon-like peptide-1) and GIP (glucose-dependent insulinotropic polypeptide).
Why the whole drug class is built on it
Natural incretins are powerful but short-lived — an enzyme breaks GLP-1 down in a couple of minutes. The breakthrough behind modern weight-loss and diabetes medications was engineering molecules that trigger the same receptors while resisting that breakdown, so a single weekly injection keeps working for days. That’s why these drugs are called incretin mimetics: semaglutide copies GLP-1, and tirzepatide copies both GLP-1 and GIP at once.
Understanding the incretin is the key that unlocks the rest of the vocabulary — agonist, receptor, dual agonist — because every one of those terms describes how a drug interacts with this natural system.