In addition to behavior modifications including body weight reduction, aerobic exercise, and smoking cessation, hypoglycemic drugs that reduce acute glucose fluctuations, such as glinides, α-glucosidase inhibitors and DPP-4 inhibitors, and hypoglycemic drugs that ameliorate insulin sensitivity, such as thiazolidinediones and metformin, are expected to improve endothelial function in patients with diabetes mellitus. This evidence concerns the gene DPP4 and diabetes mellitus.