Incretin

Definition

An incretin is a metabolic hormone released by the gastrointestinal tract in response to nutrient ingestion that potentiates glucose-dependent insulin secretion from pancreatic beta cells. The two primary incretins are GLP-1 (Glucagon-Like Peptide-1) and GIP (Glucose-dependent Insulinotropic Polypeptide).

The Incretin Effect

The incretin effect describes the observation that oral glucose administration produces a significantly greater insulin response than an equivalent intravenous glucose load. This is because oral nutrients stimulate incretin release from gut endocrine cells, which then amplifies beta cell insulin secretion. In healthy individuals, incretins account for approximately 50–70% of postprandial insulin secretion.

The incretin effect is impaired in type 2 diabetes, which provided the therapeutic rationale for developing incretin-based therapies. Notably, while GLP-1 responsiveness is preserved in T2D, GIP responsiveness is diminished — which initially led to greater clinical focus on GLP-1 agonism.

Relevance to Peptide Research

Incretin biology underpins the largest class of peptide therapeutics in current clinical use. GLP-1 receptor agonists (semaglutide, liraglutide, exenatide) and dual/triple incretin agonists (tirzepatide, retatrutide, survodutide) all leverage incretin physiology. The discovery that incretin receptor agonists produce significant weight loss beyond glucose control has transformed the field and expanded research into metabolic, cardiovascular, and neurological applications.

Related Peptides

Peptide profiles that reference “Incretin” in their research content.