Effects of chronic hyperglycaemia on incident stroke in Hong Kong Chinese patients with type 2 diabetes

BACKGROUND: It remains unclear whether hyperglycaemia as measured by HbA(1c) is a significant risk factor for stroke in patients with type 2 diabetes mellitus (T2DM). METHODS: A case-control study nested in a prospective cohort with 1 : 3 controls matched on age, gender, systolic blood pressure and low-density lipoprotein cholesterol (LDL-C) was conducted. The case group included 105 patients who developed incident stroke during 2.88 years (SD: 1.59) of follow-up of 4150 T2DM patients and 299 matched patients without incident stroke, used as the control group. Stratified Cox proportional hazard regression was used to obtain hazard ratio (HR). RESULTS: Median age was 71 years (IQR: 9.0 for the case and 10.0 for the control). HbA(1c) was significantly higher in the cases than in the controls (median 8.0% [IQR: 2.0] versus 7.2% [2.1], p < 0.0001). After controlling for smoker status, haematocrit, drug treatments and other covariates, 1% increase in HbA(1c) was associated with 1.49 (95% CI: 1.18-1.88, p = 0.0008) folds risk of occurrence of incident stroke. Patients with a history of coronary heart disease (CHD) were also at increased risk of stroke (HR: 8.25, 95% CI: 2.22-30.73, p = 0.0016). Smoker status and haematocrit were marginally significant predictors of incident stroke. Every adjusted month using lipid-lowering drugs was significantly associated with reduced risk of incident stroke (HR: 0.95, 95% CI: 0.90-0.99, p = 0.0199). Similar analysis using ACEI or ARB as a drug group was marginally significant (p = 0.0555). CONCLUSION: Chronic hyperglycaemia is a risk factor of stroke in Chinese patients with T2DM.