2 GIT hormones: glucose dependant insulinotropic polypeptide (GIP) and glucagon like peptide-1 (GLP-1) which are secreted in response to oral meals especially carbohydrates have the ability to stimulate insulin secretion from β-cells under normal physiological conditions. This insulin stimulatory power was called the (Incetin effect), and it was found to be very much defective in type 2 diabetes mellitus. Nowadays there are a lot of theraputic trials for diabetic patients based on the incretin effect, especially GLP-1 hormone which gives very promising results in therapeutic studies.