Association between diabetes mellitus and the occurrence and outcome of intracerebral hemorrhage

Objective: Whether diabetes mellitus (DM) is a risk factor for spontaneous intracerebral hemorrhage (ICH) and influences outcome after ICH remains unclear. Methods: One reviewer searched Ovid MEDLINE and Embase 1980-2014 inclusive for studies investigating the associations between DM and ICH occurrence or DM and ICH case fatality. Two reviewers independently confirmed each study's eligibility, assessed risk of bias, and extracted data. One reviewer combined studies using random effects meta-analysis. Results: Nineteen case-control studies involving 3,397 people with ICH and 5,747 people without ICH found an association between DM and ICH occurrence (unadjusted odds ratio [OR] 1.23, 95% confidence interval [CI] 1.04-1.45; I-2 = 22%), which did not differ between 17 hospital-based and 2 population-based studies (p(diff) = 0.70), and was similar in the 16 studies that controlled for age and sex (unadjusted OR 1.15, 95% CI 0.95-1.40; I-2 = 14%). This association was not identified in 3 population-based cohort studies in which ICH occurred in 38 (0.66%) of 5,724 people with DM and 448 (0.57%) of 78,702 people without DM (unadjusted risk ratio [RR] 1.27, 95% CI 0.68-2.36; I-2 = 69%). DM was associated with a higher case fatality by 30 days or hospital discharge in 18 cohort studies involving 813 people with DM and 3,714 people without DM (unadjusted RR 1.52, 95% CI 1.28-1.81; I-2 = 49%). Conclusions: The findings suggest that there may be modest associations between DM and ICH occurrence and outcome, but further information from large, population-based studies that account for confounding is required before the association can be confirmed.