High normal blood pressure, hypertension, and the risk of type 2 diabetes in Japanese men. The Osaka Health Survey.

OBJECTIVE: To investigate the relationship between high normal blood pressure or hypertension and the risk of developing type 2 diabetes in a large Japanese cohort. RESEARCH DESIGN AND METHODS: We enrolled 7,594 Japanese men aged 35-60 years who did not have diabetes or impaired fasting glucose at study entry. Type 2 diabetes was defined as a fasting plasma glucose level of or = 126 mg/dl or a 2-h postload plasma glucose level of or = 200 mg/dl. High normal blood pressure was defined as no history of hypertension and a systolic blood pressure of or = 130 and 140 mmHg or a diastolic blood pressure of or = 85 and 90 mmHg. Subjects were considered to have hypertension if they had a systolic blood pressure or = 140 mmHg, if they had a diastolic blood pressure or = 90 mmHg, or if they were taking anti-hypertensive medications. RESULTS: We confirmed 600 cases of type 2 diabetes during the 72,946 person-years of follow-up. Both high normal blood pressure and hypertension were associated with the risk of type 2 diabetes. Compared with normotensive men, men with high normal blood pressure had a multiple adjusted relative risk (RR) of 1.39 (95% CI 1.14-1.69), and men with hypertension had a multiple adjusted RR of 1.76 (1.43-2.16). Even among lean men (BMI 22.7 kg/m2), men with high normal blood pressure had a multiple adjusted RR of 1.71 (1.20-2.42), and men with hypertension had a multiple adjusted RR of 2.02 (1.34-3.05) compared with normotensive men. CONCLUSIONS: High normal blood pressure and hypertension are associated with an increased risk of developing type 2 diabetes.