Stroke is the second most frequent cause of death, resulting in 20% of deaths in diabetic patients. The relative risk of stroke is increased on average by 3-to-5 fold in the diabetic population, and diabetes itself is a risk factor for ischemic stroke and recurrence. Patients with diabetes, particularly those with type 2 diabetes, often have multiple risk factors for ischemic stroke, including hypertension, dyslipidemia, smoking, obesity and physical inactivity. However, the association between hyperglycemia and ischemic stroke is not as unequivocally described as that between hyperglycemia and coronary heart disease. Here we review the impacts of diabetes and hyperglycemia on ischemic stroke outcomes. (Korean Clinical Diabetes J 11:276-280, 2010)