Incretin effect
Category: Physiology · Last updated
The incretin effect is the observation that oral glucose elicits a substantially greater insulin response than an equivalent intravenous glucose load that produces the same plasma glucose curve. The difference reflects the action of intestinal hormones (incretins) released in response to nutrient passage through the gut.
The two incretins
- GLP-1 (Glucagon-Like Peptide 1) · secreted by intestinal L-cells; ligand of the GLP-1_receptor
- GIP (Glucose-dependent Insulinotropic Polypeptide) · secreted by intestinal K-cells; ligand of the GIP_receptor
Together, GLP-1 and GIP account for ~70% of postprandial insulin secretion in healthy adults. In type 2 diabetes, the incretin effect is blunted, particularly the GIP component.
Relevance to research peptides
The synthetic peptides in this catalog that engage incretin biology — Semaglutide, Liraglutide, Tirzepatide, Retatrutide — exploit the incretin effect by acting as long-acting receptor agonists at either GLP-1R alone or in combination with GIPR (tirzepatide) or GIPR + GCGR (retatrutide).