Aims/hypothesis: The aim of this study was to examine the relationship between type 2 diabetes and risk of ischaemic stroke in Asian populations.
Methods: We conducted a 17-year prospective cohort study in 10,582 Japanese individuals (4287 men and 6295 women) aged 40-69 years living in five communities in Japan. All subjects were free of stroke and CHD at baseline. Diabetes was defined as a fasting glucose level of >/=7.0 mmol/l, a non-fasting glucose of >/=11.1 mmol/l, or receiving medication for diabetes.
Results: The risk of non-embolic ischaemic stroke was approximately two-fold higher in diabetic subjects than in subjects with normal glucose levels. The multivariate relative risk after adjustment for age, community, hypertensive status, BMI, triceps and subscapular skinfold thickness (TSF and SSF), and other known cardiovascular risk factors was 1.8 (95% CI 1.0-3.2) for men and 2.2 (1.2-4.0) for women. This excess risk was primarily observed among non-hypertensive subjects and individuals with higher values for measures of adiposity (BMI, TSF and SSF values above the median), particularly those with higher values for SSF. The association between non-embolic ischaemic stroke and glucose abnormality was particularly strong among non-hypertensive subjects with higher SSF values: the multivariate relative risk was 1.9 (1.0-3.7) for borderline diabetes and 4.9 (2.5-9.5) for diabetes.
Conclusions/interpretation: In this cohort, type 2 diabetes was a significant risk factor for non-embolic ischaemic stroke, particularly in non-hypertensive and non-lean individuals. Due to the nationwide decrease in blood pressure and increase in mean BMI among the Japanese population, with current levels approaching those observed in Western countries, the impact of glucose abnormalities on risk of ischaemic stroke represents a forthcoming public health issue in Japan.