To investigate the risk of developing type 2 diabetes according to blood pressure (BP) levels and presence or absence of hypertensive treatment.
Design and method:
Methods:This 5-year cohort study comprised 3,508 Japanese adults aged 30–74 years without diabetes who had undergone a medical checkup including a 75-g oral glucose tolerance test between April 2008 and March 2009 at Saku Central Hospital. Participants receiving antihypertensive treatment were categorized into controlled hypertension (<140/90 mmHg) or uncontrolled hypertension (140/90 mmHg or higher) groups. Participants not receiving antihypertensive treatment were categorized according to the definition of the Japan Society of Hypertension: optimal BP (less than 120/80 mmHg), normal BP (120–129/80–84 mmHg), high-normal BP (130–139/85–89 mmHg), grade I hypertension (140–159/90–99 mmHg) and grade II/III hypertension (160/100 mmHg or higher). Hazard ratios (HRs) and 95% confidence intervals (CIs) for the incidence of type 2 diabetes as defined by the 75-g oral glucose tolerance test were estimated using multivariable-adjusted Cox proportional hazard models in reference to optimal BP.
During the follow-up, 295 participants developed type 2 diabetes. Those with high-normal BP, grade I hypertension, grade II/III hypertension and uncontrolled hypertension were at significantly higher risk for developing type 2 diabetes, with HRs (95% CIs) of 1.53 (1.03–2.29), 1.53 (1.02–2.32), 2.19 (1.01–4.77) and 1.81 (1.10–2.99), respectively.
Compared with those with optimal BP, individuals with BP 130/85 mmHg or higher not receiving antihypertensive treatment and uncontrolled hypertensives with BP 140/90 mmHg or higher receiving antihypertensive treatment were at a significantly higher risk for developing type 2 diabetes.