BACKGROUND: Although diabetes mellitus (DM) is a risk factor for stroke, it is unclear whether stroke features are different in diabetic vs nondiabetic individuals. OBJECTIVE: To assess the role of DM in stroke patients. METHODS: Risk factors, etiology, lesion topography, clinical features, and outcome were assessed in 611 diabetic individuals (history of DM or fasting plasma glucose level of > or =7.0 mmol/L) among 4,064 consecutive patients of the Lausanne Stroke Registry. RESULTS: Patients with DM were 5.3 years older than non-DM patients. After multivariate analysis, DM was associated with lower relative prevalence of intracerebral hemorrhage (ICH; odds ratio [95% CI]: 0.63 (0.45 to 0.9); p = 0.022), higher relative prevalence of subcortical infarction (SCI; 1.34 [1.11 to 1.62]; p = 0.009), and higher relative frequency of small-vessel (SVD; 1.78 [1.31 to 3.82]; p = 0.012) and large-artery (LAD; 2.02 [1.31 to 2.02]; p = 0.002) disease. In the cohort of diabetic stroke patients, there was no interaction of DM with either hypertension or age for the outcomes of ICH, SCI, SVD, and LAD. Moderate to severe deficit on admission (31.1 vs 31.6%; p = 0.4) and poor functional outcome at 1 month (14.1 vs 15.3%; p = 0.24) did not differ in patients with DM compared with non-DM patients. In multivariate analysis, neither DM (0.86 [0.63 to 1.11]; p = 0.15) nor hypertension (1.09 [0.91 to 1.39]; p = 0.32) was associated with poor functional outcome. CONCLUSIONS: Diabetic stroke patients are associated with specific patterns of stroke type, etiology, and topography but not with poor functional outcome. There was no interaction between DM and hypertension or age. [Authors]