The risk of having a cerebrovascular accident (CVA) is approximately 3 to 5 times greater in the diabetic population than in non-diabetics. The physiopathological mechanisms of CVAs in patients with diabetes mellitus are not well-known, since few studies of this have been done.To verify the hypothesis that intracranial arteriosclerosis, interpreted from findings of stenosis on intracranial Doppler studies, is greater in diabetics than in non-diabetics, independently of other vascular risk factors.Patients were selected from the Register of Cerebrovascular Diseases of the Neurology Department of the Hospital de Santa Maria as having had an ischemic cerebrovascular accident (CVA)/transient ischemic accident (TIA), assessed by a colour codified vertebral carotid eco-Doppler and transcranial Doppler. Intracranial changes in the diabetic and non-diabetic groups of patients were compared with relation to the presence of risks such as hypercolestrolaemia, arterial hypertension and smoking.384 patients were included, 71 were diabetic and 313 non-diabetic. The two groups were comparable with regard to average age and sex. Intracranial stenosis was approximately 3.13 (95% CI = 1.69-5.79) times more frequent in the diabetic population than in non-diabetics. This difference persisted independently of the presence or absence of other vascular risk factors.Diabetes mellitus is an important independent risk factor of alterations in the intracranial blood vessels and therefore of CVA. The intracranial circulation should be studied in these patients in view of the great frequency of intracranial stenoses and possible future improvements with therapeutic intervention.