Diabetes as risk factor for transient ischaemic attacks as opposed to strokes.

This study examined the hypothesis that diabetes mellitus predisposes the brain to irreversible ischaemic damage rather than to reversible transient ischaemic attacks. Of 525 patients presenting with transient or minor strokes, 54 patients were found to have diabetes mellitus and 471 patients had no evidence of diabetes. The diabetic subgroup was significantly more hypertensive than the non-diabetic subgroup (P less than 0.001). In an overall comparison of the prevalence of strokes and transient ischaemic attacks in diabetic and non-diabetic subgroups, 26 (6.7%) of 388 patients with transient ischaemic attacks had diabetes mellitus, and 362 (93.3%) of 388 patients with transient ischaemic attacks were non-diabetic. Thus diabetes was not a significant risk factor for TIAs (P less than 0.001). However when the role of diabetes in causing strokes was assessed in all 525 patients evaluated in the study, 28 of 54 diabetics presented with strokes whereas 109 of 471 non-diabetics presented with strokes. Statistically diabetics were 3-4 times more likely to present with a stroke than non-diabetics (P less than 0.0001) in keeping with the findings in other centres. The findings of this study appear to support the hypothesis that diabetics are at a greater risk of permanent cerebral ischaemia without prior warning of a transient ischaemic event than their non-diabetic counterparts. It may be advisable to screen asymptomatic diabetic patients aggressively and to consider these patients as a high risk subgroup for potential stroke if extracranial carotid vascular disease is present.