Dipeptidyl Peptidase-4 Inhibitor, Sitagliptin, Improves Endothelial Dysfunction in Association With Its Anti-Inflammatory Effects in Patients With Coronary Artery Disease and Uncontrolled Diabetes

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Background: Dipeptidyl peptidase 4 (DPP4) inhibitors are used for treatment of diabetes mellitus (DM). We hypothesized that sitagliptin, a DPP4-inhibitor, could improve endothelial dysfunction in DM patients with coronary artery disease (CAD). Methods and Results: The 40 patients with CAD and uncontrolled DM, aged 68.7±9.4 years (mean±standard deviation) (50% males, hemoglobin A_1c [HbA_1c] 7.4±1.0%) were assigned to either additional treatment with sitagliptin (50mg/day, n=20) or aggressive conventional treatment (control, n=20) for 6 months. Endothelial function was assessed by the reactive hyperemia peripheral arterial tonometry index (RHI). The clinical characteristics at baseline were not different between the groups. After treatment, fasting blood glucose and insulin levels, and lipid profiles were not different between the groups. HbA_1c levels significantly improved similarly in both groups. The percent change in RHI was greater in the sitagliptin group than in the control group (62.4±59.2% vs. 15.9±22.0%, P<0.01). Furthermore, treatment with sitagliptin resulted in a significant decrease in the high-sensitivity C-reactive protein (hsCRP) level, but no such change was noted in the control group. Linear regression analysis demonstrated a significant negative relation between changes in RHI and hsCRP, but not between RHI and HbA_1c. Conclusions: Sitagliptin significantly improved endothelial function and inflammatory state in patients with CAD and uncontrolled DM, beyond its hypoglycemic action. These findings suggest that sitagliptin has beneficial effects on the cardiovascular system in DM patients.