Relative nocturnal hypertension in children with insulin-dependent diabetes mellitus.

Twenty-four-hour blood pressure and heart rate measurements were carried out in 14 newly diagnosed diabetics and in 28 diabetics with 5-13 years' duration of the disease; 8 healthy children were used as controls. Mean arterial blood pressure increased at night in 5, decreased slightly (less than 10%) in 5 and decreased markedly (more than 10%) in 18 diabetics with longer duration of the disease. The diurnal-nocturnal differences in heart rates were significantly lower in diabetics with relative "nocturnal hypertension" compared to the control group (p < 0.05). A significant negative correlation was found between maximal arterial blood pressure during physical exercise and the diurnal-nocturnal differences in mean arterial blood pressure in diabetics (r = -0.58; p < 0.02). In conclusion, we found elevated nocturnal blood pressure in a subgroup of children with longer duration of diabetes and without increased albumin excretion. However, longitudinal studies of blood pressure profiles are needed to identify the candidates for diabetic vasculopathy among diabetic children.