DPP4 and type 2 diabetes mellitus: As stromal cell-derived factor-1 (SDF-1) is an endogenous DPP4 substrate which can mobilize endothelial progenitor cells to sites of vascular or myocardial injury, it is intriguing that DPP4 inhibition enhances SDF-1, improves cardiac function and survival after acute myocardial infarction in mice, and increases circulating endothelial progenitor cells in patients with T2DM (Zaruba et al., 2009; Fadini et al., 2010).