Cardiovascular disease is the main cause of increased mortality in diabetes patients. Myocardial infraction and stroke is in 60% to 80% causes reason of death in patients with type 2 diabetes mellitus. The main risk factor of cardiovascular disease is hyper-glycemia, hyperinsulinaemia and hypertension. The other arteriosclerosis risk factors are for example smoking. We measure the concentration of ascorbic acid in smokers' diabetes patients with type 2 diabetes mellitus with stable coronary disease scheduled for coronary artery bypass grafting (CABG). Vitamin C is assumed to be a basic antioxidant although its role in pathological conditions is controversial. However, it seems that the complexity of the oxidant-antioxidant system makes the question of participation of ascorbic acid in pathogenesis of diseases still open. Determination of the role of ascorbic acid concentration in pathogenesis of diabetic angiopathy may be of significant importance in the their effective therapy.