Diabetes Mellitus Is Associated With Increased Risk of Ischemic Stroke in Patients With and Without Coronary Artery Disease

Background and Purpose- Diabetes mellitus (DM) and non-DM patients without coronary artery disease (CAD) have a similar low risk of myocardial infarction after coronary angiography. The risk of ischemic stroke in DM patients dependent on CAD status is less explored. We examined whether DM patients without CAD have a risk of ischemic stroke similar to that in patients with neither DM nor CAD. Methods- We conducted a cohort study of patients who underwent coronary angiography between 2004 and 2012 in Western Denmark. Patients diagnosed with previous ischemic stroke or transient ischemic attack were excluded. Patients were stratified according to the presence of DM and CAD. Follow-up started 30 days after coronary angiography. We computed event rates and adjusted incidence rate ratios using patients without DM or CAD as reference. We examined the trend between CAD extent and ischemic stroke in patients with DM. Results- A total of 81 909 patients were included. Median follow-up was 3.8 years. Patients with both DM and CAD were at the highest risk of ischemic stroke (1.32 events per 100 person-years; adjusted incidence rate ratio, 2.00 [95% CI, 1.72-2.32]). Patients with CAD alone (0.77 events per 100 person-years; adjusted incidence rate ratio, 1.27 [95% CI, 1.12-1.44]) or DM alone (0.95 events per 100 person-years; adjusted incidence rate ratio, 1.74 [95% CI, 1.42-2.15]) were at intermediate risk, whereas patients with neither DM nor CAD (0.52 events per 100 person-years) were at the lowest risk. Among patients with DM, extent of CAD was further predictive of risk (P_trend<0.001). Conclusions- Not only CAD but also DM are associated with the risk of ischemic stroke after coronary angiography. Their combination further increases the risk of ischemic stroke depending on the extent of CAD.