Atherosclerosis is the leading cause of death in patients with diabetes mellitus, increasing mortality in all forms of the disease. Classical risk factors, including hyperlipidemia, hypertension and obesity, do not completely account for the increased incidence of atherosclerosis in diabetes. Some platelet activation markers such as CD62P, CD63, PAC-1, Annexin V and platelet-derived microparticles (PDMP) are elevated in patients with diabetes, since diabetic platelets often have increased sensitivity to secondary aggregation in response to agonist. PDMPs are thought to play a role in clinical disease because they express phospholipids that function as procoagulants. High shear stress can initiate both platelet aggregation and shedding of procoagulant-containing PDMP, suggesting that PDMP generation by high shear stress occurs in small diseased arteries and arterioles under various clinical conditions. Platelet activation markers were significantly higher in the hypertensive or hyperlipidemic patients than in the controls. Selectins and cell adhesion molecules were also higher in the hypertensive or hyperlipidemic patients, and they were significantly higher in these patients with diabetes. Activated microparticles and PDMP may contribute to the development of atherosclerosis in diabetes, and platelet activation markers seem to be useful for the assessment of vascular damage in these patients.