DPP4 and type 2 diabetes mellitus: The aim of the present study is to evaluate the effect of sitagliptin, a DPP-4 inhibitor, on the longitudinal change in the GSM value, an index of the ultrasonic tissue characteristics of the carotid wall, in patients with T2DM, using data obtained from the Sitagliptin Preventive study of Intima-media thickness Evaluation (SPIKE) trial [22].