This study evaluated the aetiological factors for cerebrovascular attack (CVA) using echocardiography and sonography of the carotid arteries. Results from 253 patients with CVA were evaluated retrospectively and analysed according to the presence or absence of diabetes and atrial fibrillation. In patients with sinus rhythm (n = 182), the presence of diabetes was associated with an increased incidence of atherosclerotic changes and significant stenosis of the carotid artery as well as greater intima-media thickness. In contrast, when evaluating signs of thromboembolic risk, there were no statistically significant differences in left atrial diameter or left ventricular ejection fraction between the two groups. In patients with atrial fibrillation (n = 71), no significant differences were observed between diabetic and non-diabetic patients in any of the parameters measured. These findings suggest that the increased risk of ischaemic CVA in diabetic patients is due to atherosclerosis in the carotid vessels rather than embolism of cardiac origin.