Diabetic vascular disease, especially cardiovascular disease is the leading cause of death in patients with Type 2 diabetes mellitus （T2DM）. It has been shown that metformin goes beyond mere glycemic control, increasing insulin sensitivity. Moreover, metformin can decrease markers of inflammation, contribute to the reduction of oxidative stress, improve vascular endothelial and clock function. Therefore, metformin may have protective effect on diabetic macrovascular complication, which is independent of its hypoglycemic effect.