As for the relationship between a DPP-4 inhibitor and endothelial function in the conduit brachial artery assessed by flow-mediated vasodilation (FMD), a previous short-term study demonstrated that 6-week treatment with DPP-4 inhibitors, including sitagliptin and alogliptin, attenuated FMD [11], whereas other previous studies demonstrated that 12-week treatment with sitagliptin improved FMD in patients with type 2 diabetes [12, 13]. This evidence concerns the gene DPP4 and type 2 diabetes mellitus.