[Circadian rhythm of blood pressure and heart rate in hypertension with type 2 diabetes mellitus].

Hypertension is an important risk factor for cardiovascular complications of diabetes. Most of the studies performed in diabetics so far, however, have dealt with the assessment of blood pressure by traditional sphygmomanometry. In order to investigate the circadian pattern of blood pressure and heart rate in patients with different categories of glucose tolerance, we performed ambulatory blood pressure monitoring in 28 obese hypertensives without clinical nephropathy divided in two groups. Group A consisted of 14 hypertensive males with type 2 diabetes mellitus (mean age 49.7 +/- 7.1 years, mean duration of diabetes 4.0 +/- 2.9 years); group B consisted of 14 hypertensive males with normal glucose tolerance according to National Diabetes Data Group (mean age 47.2 +/- 7.1 years). There was no significant difference in casual blood pressure (151.4/104.8 in group A versus 148.5/104.2 mmHg in group B). Ambulatory blood pressure monitoring revealed significantly higher systolic blood pressure in group A during the day (162.2 +/- 12.1 vs 152.1 +/- 9.0 mmHg in group B, P < 0.05) and at night (141.0 +/- 13.2 vs 125.5 +/- 12.5 mmHg in group B, P < 0.005). That suggests that casual readings underestimate systolic blood pressure as a predictor for macrovascular events in type 2 diabetics. The decline in nocturnal heart rate was significantly lower in group A (11.2 +/- 5.2 min-1) in comparison to group B (16.9 +/- 7.0 min-1; P < 0.05) suggesting reduced parasympathetic tone at night in diabetic patients. We conclude that type 2 diabetes has significant influence on systolic blood pressure and heart rate 24-h profiles even in patients without diabetic nephropathy.