incretum

Incretum refers to a group of gastrointestinal hormones that are released after food intake and stimulate insulin secretion. The two primary incretin hormones are glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP). These hormones are secreted by enteroendocrine cells in the small and large intestines in response to the presence of nutrients in the digestive tract.

Upon release, incretins travel through the bloodstream to the pancreas. There, they bind to specific receptors on the beta cells, prompting them to release more insulin. This insulin release is glucose-dependent, meaning that incretins stimulate insulin secretion only when blood glucose levels are elevated, thus helping to prevent hypoglycemia. In addition to stimulating insulin secretion, GLP-1 also suppresses glucagon release from the alpha cells of the pancreas, which further contributes to lowering blood glucose levels. GLP-1 also has effects on gastric emptying, slowing it down, and promoting satiety, which can aid in weight management.

The incretin effect is diminished in individuals with type 2 diabetes. This reduced incretin effect contributes to impaired glucose control in these patients. Consequently, therapeutic strategies targeting the incretin system have been developed. These include dipeptidyl peptidase-4 (DPP-4) inhibitors, which block the enzyme that degrades incretins, thereby increasing their circulating levels and prolonging their action. Another class of drugs are GLP-1 receptor agonists, which mimic the action of GLP-1 by directly stimulating GLP-1 receptors. Both approaches have proven effective in improving glycemic control in people with type 2 diabetes.