Cardiovascular prognosis of sustained and white-coat hypertension in patients with type 2 diabetes mellitus

OBJECTIVE: Cardiovascular prognosis in diabetic white-coat hypertension (WCH) has not yet been described. We designed this study to investigate the impact of WCH on cardiovascular events in patients with type 2 diabetes, compared with those having type 2 diabetes along with sustained hypertension (SH), and with nondiabetic hypertensive individuals. METHODS: We performed ambulatory blood pressure (BP) monitoring in 1207 consecutive hypertensive patients at baseline, and they were followed up for 49±22 months. The mean age was 70.7±9.8 years; 262 had type 2 diabetes; and 945 did not. They were classified as having SH with diabetes (n=210); diabetic WCH (n=52); SH alone (n=719); or WCH alone (n=226), using awake BP of 135/85 mmHg as the cutoff value. Cox regression models were used to calculate hazard ratios (HR) and 95% confidence intervals of the risk for cardiovascular events, after controlling for age, sex, body mass index, current smoking, serum creatinine, and clinical systolic BP. RESULTS: During the follow-up period, 97 cardiovascular events occurred. The incidence of cardiovascular events in the diabetic SH group was significantly higher than in the diabetic WCH, nondiabetic SH, and nondiabetic WCH (P<0.05; log-rank test) groups. In Cox regression analysis, the diabetic SH group had significantly higher risk of cardiovascular events compared with the diabetic WCH group (HR: 8.2; 95% confidence intervals: 1.09-61.8; P=0.04). Although nonsignificant, the HRs in the SH and WCH groups, relative to diabetic WCH, exceeded 3.0. CONCLUSIONS: The cardiovascular prognosis for diabetic WCH was better than that for diabetic SH during 4 years of follow-up.