inkretins

Inkretins are a group of gastrointestinal hormones that play a significant role in regulating blood glucose levels. The primary inkretins are glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP). These hormones are released by enteroendocrine cells in the small and large intestines in response to nutrient intake, particularly carbohydrates and fats.

Upon secretion, inkretins act on various target tissues. Their most well-known effect is the potentiation of glucose-stimulated insulin secretion from the pancreatic beta cells. This means that when blood glucose levels are high, inkretins signal the pancreas to release more insulin, thereby helping to lower blood sugar. Conversely, they inhibit glucagon secretion from pancreatic alpha cells, which further reduces glucose production by the liver.

Beyond their direct effects on the pancreas, inkretins also influence gastric emptying and satiety. They slow down the rate at which food leaves the stomach, which contributes to a feeling of fullness and can help reduce food intake. The inkretin effect refers to the observation that oral glucose administration elicits a greater insulin response than intravenous glucose administration, even when plasma glucose levels are matched. This difference is attributed to the inkretins released from the gut.

Due to their beneficial effects on glucose homeostasis, inkretins have become a target for the treatment of type 2 diabetes. Medications that mimic or enhance the action of inkretins, such as GLP-1 receptor agonists and dipeptidyl peptidase-4 (DPP-4) inhibitors, are widely used to improve glycemic control in diabetic patients.