Incretin

- 2 main incretins, GLP-1 (glucagon-like peptide-1) and GIP (glucose dependent insulinotropic peptide)
- secreted by L cells of ileum and colon
- incretin effect: insulin response to oral glucose is better than intravenous glucose
- promotes glucose induced insulin release from pancreatic beta cells, delays rate of gastric emptying, promotes satiety, reduce appetite in brain
- suppress postprandial glucose secretion
- GLP-1 analogue (exenatide) is given by twice daily subcutaneous injection
- dipeptidyl peptidase 4 (DPP4) rapidly inactivates GLP-1. DPP4 inhibitor (sitagliptin or vildagliptin)