Diabetes Mellitus A Risk Factor for Ischemic Stroke in a Large Biracial Population

Background and Purpose-We previously reported increased incidence of ischemic stroke among both blacks and whites with diabetes mellitus, especially in those aged <55 years. With rising prevalence of diabetes mellitus in the past decade, we revisit the impact of diabetes mellitus on stroke incidence in the same population (approximate to 1.3 million) 5 and 10 years later. Methods-This is a population-based study. First ischemic strokes among black and white residents of the 5-county Greater Cincinnati/Northern Kentucky region, aged >= 20 years, for periods 7/1993 to 6/1994, 1999, and 2005, were included in this analysis. Incidence rates were adjusted for sex, race, and age, as appropriate, to the 2000 US population. Results-History of diabetes mellitus among first ischemic strokes was reported for 493/1709 (28%) in 1993/1994, 522/1778 (29%) in 1999, and 544/1680 (33%) in 2005. Risk ratios (95% confidence interval) for rates of stroke in those with versus without diabetes mellitus for blacks reduced significantly from 5.6 in 1993/1994 to 3.2 in 2005; for whites the risk ratio remained stable at 3.8 in 1993/1994 and 2005. However, risk ratios varied with age, with an overall 5- to 14-fold increased risk observed in those aged 20 to 65 years. Conclusions-Those with diabetes mellitus remain at greatly increased risk for stroke at all ages, especially <65 years, regardless of race. The rates and risk ratios for 1999 and 2005, although similar to those previously reported for the mid-1990s, take on increased significance, given the epidemic of diabetes mellitus and metabolic syndrome throughout the US and the world.