Incretin
Also called: incretin hormones
Clinical reviewer: Jacob Moore, MD · Last checked September 16, 2026
What is an incretin hormone?
Incretin refers to a class of gut hormones, GIP and GLP-1, that boost insulin release after eating more than glucose alone would trigger. This "incretin effect" is markedly reduced in type 2 diabetes, and GLP-1 medications are built on incretin biology.
What is the "incretin effect"?
When glucose is taken by mouth, the body releases more insulin than an identical rise in blood glucose delivered directly into a vein would produce; that extra insulin secretion is the incretin effect, driven by the gut hormones GIP and GLP-1 [1]. In type 2 diabetes, this effect is markedly reduced or absent, largely because GIP's ability to stimulate insulin secretion is impaired [1].
How do GIP and GLP-1 differ as incretins?
GIP's insulinotropic potency is much more impaired in type 2 diabetes than GLP-1's, so exogenous GLP-1 can still stimulate insulin secretion, suppress glucagon and lower glucose in people with diabetes [1]. That is why early incretin-based medicines targeted GLP-1 alone, before researchers began combining GIP and GLP-1 receptor activity in one molecule [1].
How do GLP-1 medications build on incretin biology?
Incretin-based, glucose-lowering medications include selective GLP-1 receptor agonists and newer co-agonists that stimulate both the GIP and GLP-1 receptors [1]. Tirzepatide, a GIP/GLP-1 receptor co-agonist, lowers HbA1c and body weight more than selective GLP-1 receptor agonists such as semaglutide [1]. This strategy of activating multiple incretin receptors in one molecule is the basis of newer dual agonist drugs [2].
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This entry is for education and is not medical advice. Talk with a licensed clinician about your own situation before starting, stopping, or changing any treatment.
