The Incretin Effect: GIP & GLP-1 in Research
The incretin effect describes the phenomenon where oral glucose produces a greater insulin response than intravenous glucose at the same blood glucose levels. This effect, mediated by gut-derived hormones GIP and GLP-1, is the foundation for modern metabolic peptide research.
What Are Incretins?
Incretins are gut hormones released after food intake that enhance insulin secretion. The two primary incretins are: GLP-1 (glucagon-like peptide-1) — produced by intestinal L-cells, targets GLP-1 receptors on beta cells. GIP (glucose-dependent insulinotropic polypeptide) — produced by intestinal K-cells, targets GIP receptors on beta cells. Together, they account for 50-70% of post-meal insulin secretion.
GLP-1 in Research
GLP-1 research peptides like semaglutide mimic endogenous GLP-1 with modified structures for extended half-life. GLP-1 effects include: glucose-dependent insulin secretion, glucagon suppression, slowed gastric emptying, central appetite reduction, and potential beta cell preservation.
GIP in Research
GIP was once considered less promising than GLP-1, but the success of tirzepatide (a GIP/GLP-1 dual agonist) renewed interest. GIP receptor activation provides: enhanced insulin secretion, improved lipid metabolism, potential bone-protective effects, and complementary weight management effects when combined with GLP-1.
Triple Agonism
Retatrutide adds glucagon receptor agonism to the GIP/GLP-1 combination. Glucagon receptor activation increases energy expenditure, enhances hepatic fat oxidation, and may contribute to superior metabolic outcomes in research.
Related Articles: How GLP-1 Agonists Work | Semaglutide vs Tirzepatide | GLP-1 Overview
For research use only. Shop incretin peptides with third-party COAs at Proxiva Labs.