NOS3 and diabetes mellitus: The major sources of ROS in endothelial cells include mitochondrial electron transport, NADPH oxidase, xanthine oxidase, uncoupled eNOS, and cytochrome P450 enzymes.11 It is known that mtROS are biologically important mediators and the concept of mtROS as a driving force for diabetes complications has also been widely accepted.12 However, it is unknown the effects of vildagliptin (VLD), an oral DPP‐4 inhibitor, on mtROS production and mitochondrial dysfunction in endothelium.