Activation of oxidative stress by glucose fluctuations plays a major role in the pathogenesis of diabetic complication. Dipeptidyl peptidase IV (DPP-IV), such as vildagliptin, enhances glucose-induced insulin secretion, decreases glucagon secretion, and reduces postprandial hyperglycemia and may also improve acute fluctuations of glucose. We believe that vildagliptin may exert an effect of decreasing oxidative stress by reducing glucose excursion.