Background and Purpose: Diabetes mellitus (DM) is a well-established risk factor for ischemic stroke (IS), but the literature is inconsistent on the effect of DM on outcomes after IS. We sought to determine if DM increases the risk of mortality and recurrence after IS, and if these associations are greater in Mexican Americans (MA) than non-Hispanic whites (NHW).
Methods: IS cases, all-cause mortality, and recurrent strokes were identified from the Brain Attack Surveillance in Corpus Christi (BASIC) project (2006-2012). Sociodemographics and clinical data were obtained from medical records and interviews. Cumulative mortality and stroke recurrence risk were estimated at 30 days and 1 year using Kaplan-Meier analysis and Cox proportional hazards models. Effect modification by ethnicity was examined.
Results: There were 1,301 IS cases, 46% with a history of DM, median age 70 (IQR: 58-81), and 61% MA. Patients with DM were younger and more likely to be MA compared to patients without DM. Risk of 30-day and 1-year mortality was 8.4% and 20.5% for those with DM and 9.5% and 20.8% for those without DM, respectively. Risk of 30-day and 1-year stroke recurrence was 1.2% and 7.5% for those with DM and 1.5% and 5.8% for those without DM, respectively. Unadjusted, DM was not a significant predictor of mortality or recurrence (see table). After adjustment, DM predicted mortality (30-day HR=1.58, 95% CI: 0.98-2.53; 1-year HR=1.48, 95% CI: 1.10-2.00) but not stroke recurrence (1-year HR=1.28, 95% CI: 0.78-2.08). Effect modification by ethnicity was not significant (p>0.2 for all models).
Conclusions: Given that patients with DM were significantly younger than patients without DM, the crude association between DM and mortality revealed no difference. However, after accounting for age and other factors, patients with DM were 50% more likely to die at 1 year after IS compared to patients without DM.