Abstract: The peptides, glucagon-like peptide-1 (GLP-1) and Glucose-dependent insulinotropic polypeptide, are two kinds of incretin hormones secreted by the endocrine cells of gut following nutrient absorbed. These two peptides are also called incretin, and the function of them is to promote the secretion of insulin and maintain glucose homeostasis. Because they can be quickly inactivated by Dipeptidyl peptidase -4 (DPP-4) that is widely existing in the body, inhibit the active of DPP-4 can increase the function of GLP-1 and GIP. Thereby the Islet function and glycemic controlling for T2DM will be improved. more and more drugs based on the new target are developed to use for T2DM treatment. In this review, we discuss the relationship between incretin and T2DM, and the function mechanism of GLP-1, and drugs development for T2DM such as GLP-1 mimics and DPP-4 inhibitors.