Impact of white-coat hypertension on microvascular complications in type 2 diabetes

The purpose of this study was to determine the impact of white-coat hypertension (WCH) on microvascular complications in type 2 diabetes.

A cross-sectional study was conducted in normotensive patients and patients with WCH selected from a cohort of 319 type 2 diabetic patients. Normotension was defined by office blood pressure <140/90 mmHg and daytime blood pressure <135/85 mmHg on ambulatory blood pressure monitoring (ABPM). WCH was defined as office blood pressure >or=140/90 mmHg and daytime blood pressure <135/85 mmHg on ABPM. Subjects were evaluated for diabetic nephropathy (24-h urinary albumin excretion rate) and diabetic retinopathy (classified according to the Global Diabetic Retinopathy Group).

Forty-six type 2 diabetic patients had WCH (14.4%; mean age 56.6 years; 45.3% men) and 117 had normotension (36.6%; mean age 55.8 years; 37.5% men). These groups did not differ in clinical and main laboratory characteristics. Systolic ABPM (24-h: 124.7 +/- 6.7 vs. 121.0 +/- 8.5 mmHg, P = 0.01 and daytime: 126.6 +/- 7.2 vs. 123.2 +/- 8.2 mmHg, P = 0.01) and blood pressure loads were higher in subjects with WCH than in the normotensive subjects. WCH was associated with an increased risk for macroalbuminuria (odds ratio 4.9 [95% CI 1.3-18.7], P = 0.01). On multivariate analysis models, WCH was associated with macroalbuminuria (2.0 [1.3-3.2], P = 0.02) and increased the risk for both nonproliferative and proliferative diabetic retinopathy (2.7 [1.2-6.6], P = 0.02 for any degree of diabetic retinopathy) after adjustments for confounding factors.

Type 2 diabetic patients with WCH have an increased risk for diabetic retinopathy and diabetic nephropathy. Therefore, WCH should not be considered a harmless condition, and treatment should be considered.