ABNORMAL NOCTURNAL BLOOD-PRESSURE FALL IN NORMOTENSIVE ADOLESCENTS WITH INSULIN-DEPENDENT DIABETES IS AMELIORATED FOLLOWING GLYCEMIC IMPROVEMENT

Lack of the physiological nocturnal fall in blood pressure (BP) has be en found in diabetics and it seems to be related to the presence of di abetic complications. The present study examined the changes in the no cturnal BP pattern of 8 normotensive insulin-dependent diabetic adoles cents without nephropathy following improvement in glycemic control in duced by an 8-day program of adequate diet and exercise. The same numb er of age-and sex-matched control subjects were studied. During the fu :st and eighth nights of the program, BP was obtained by ambulatory BP monitoring. After a 10-min rest, 3 BP and heart rate (HR) recordings were taken and the mean values were considered to represent their awak e values. The monitor was programmed to cuff insufflation every 20 min from 10:00 p.m. to 7:00 a.m. The glycemic control of diabetics improv ed since glycemia (212.0 +/- 91.5 to 140.2 +/- 69.1 mg/dl, P<0.03), ur ine glucose (12.7 +/- 11.8 to 8.6 +/- 6.4 g/24 h, P = 0.08) and insuli n dose (31.1 +/- 7.7 to 16.1 +/- 9.7 U/day, P<0.01) were reduced on th e last day. The mean BP of control subjects markedly decreased during the sleeping hours of night 1 (92.3 +/- 6.4 to 78.1 +/- 5.0 mmHg, P<0. 001) and night 8 (87.3 +/- 6.7 to 76.9 +/- 3.6 mmHg, P<0.001). Diabeti c patients showed a slight decrease in mean BP during the first night. However, the fall in BP during the nocturnal period increased signifi cantly on the eighth night. The average awake-sleep BP variation was s ignificantly higher at the end of the study (4.2 vs 10.3%, P<0.05) and this ratio turned out to be similar to that found in the control grou p (10.3 vs 16.3%). KR variation also increased on the eighth night in the diabetics. Following the metabolic improvement obtained at the end of the period, the nocturnal BP variation of diabetics was close to t he normal pattern. We suggest that amelioration of glycemic control ma y influence the awake-sleep BP and HR differences. This effect may be due at least in part to an attenuated insulin stimulation of sympathet ic activity.