Stroke recurrence in diabetics. Does control of blood glucose reduce risk?

Patients with diabetes are at increased risk of stroke. Risk might be reduced if blood glucose level were controlled.

In a population-based study, we enrolled 621 patients within a month of an initial ischemic stroke and followed them regularly twice annually; 198 were diabetic. We monitored blood glucose level in 142 (72%) using glycosylated hemoglobin (HbAlc). Recurrent stroke frequency was determined by history, examination, and medical records. Cox proportional hazards models were used to examine the relationship between risk of recurrent stroke and HbAlc level. The models included interaction with time-dependent HbAlc level and history of diabetes, selected medical comorbidities, age, and sex. HbAlc level was analyzed as both a continuous and a dichotomous variable (ie, controlled versus uncontrolled); "controlled" was defined with different cut points.

All but 17 patients (12%) whose blood glucose was monitored were well controlled (HbAlc < 8%). HbAlc level was not associated with increased risk of stroke recurrence (hazard ratio [HR], 0.87 per 1% increment in HbAlc; 95% confidence interval [CI], 0.623 to 1.219), nor was there a trend toward increased risk of recurrent stroke as the cut point defining "controlled" increased: with HbAlc at < 6%, the HR for the uncontrolled group was 0.51 (95% CI, 0.176 to 1.503); at < 7%, it was 0.43 (95% CI, 0.089 to 1.923); and at < 8%, it was also 0.43 (95% CI, 0.057 to 3.317).

Among diabetic patients with an initial stroke, no association between HbAlc level over time and risk of stroke recurrence was found. However, most patients in this cohort were well controlled, and any adverse effect of poor control could not be adequately tested.