Diabetes mellitus (DM) is increasing in the world wide and a risk factor for the progression of coronary artery disease (CAD). CAD is the major cause of mortality in patients with DM. In the case of combination CAD with DM becomes a great threatening of their lifes. In fact, diabetes patients have about 3-folds risk of mortality from CAD compared to non-diabetic subjects. Furthermore, patients with diabetes undergoing revascularization have worse mortality than non-diabetic patients. Optimal revascularization for CAD in the diabetic patients remains controversial, with availability of drug eluting stents and bypass surgery. Because of the worse prognosis in diabetic patients, making an effort toward an early diagnosis and aggressive medical treatment is necessary and a first step to improve their prognosis.