Background and purpose: This study was conducted to determine whether glucose intolerance and diabetes increase the risk of thromboembolic, hemorrhagic, and total stroke independent of other risk factors.
Methods: Among 7549 Japanese-American men aged 45 to 68 years and free of coronary heart disease and stroke during 1965 to 1968, history of diabetes, diabetic medication, and nonfasting glucose 1 hour after a 50-g load were used to classify subjects into four glucose tolerance categories. Incidence of stroke over 22 years was ascertained using comprehensive hospital-based surveillance. Age- and risk factor-adjusted relative risks of stroke were determined using a Cox proportional hazards model.
Results: A total of 374 thromboembolic, 128 hemorrhagic, and 36 type-unknown strokes occurred. Incidence of thromboembolic but not hemorrhagic stroke increased with worsening glucose tolerance category. Compared with the "low-normal" (glucose < 151 mg/dL) group, subjects in the "high-normal" (151 to 224 mg/dL), "asymptomatic high" (> or = 225 mg/dL), and "known diabetes" groups all had significantly elevated age-adjusted relative risks of thromboembolic stroke. After adjustment for other risk factors, relative risks remained significantly elevated for the asymptomatic high and known diabetes groups (1.43 and 2.45; 95% confidence intervals, 1.00 to 2.04 and 1.73 to 3.47, respectively). Associations were the same in hypertensive and nonhypertensive subjects and similar but slightly stronger in younger (aged 45 to 54 years) than in older (aged 55 to 68 years) men.
Conclusions: Subjects with diabetes and elevated glucose appear to be at increased risk of thromboembolic but not hemorrhagic stroke. These associations were largely independent of other cardiovascular disease risk factors. Excess risk is apparent in older as well as younger diabetic individuals and in hypertensive and nonhypertensive subjects with diabetes.