Abnormal nocturnal blood pressure fall in normmotensive adolescents with insulin-dependent diabetes is ameliorated following glycemic improvement

Lack of the physiological nocturnal fall in blood pressure (BP) has been found in diabetics an it seems to be related to the presence of diabetic complications. The present study examined the changes in the nocturnal BP pattern of 8 normotensive insulin-dependent diabetic adolescents without nephropathy following improvement in glycemic control induced by an 8-day program of adequate diet and exercise. The same number of age- and sex-matched control subjects were studied. During the first and eighth nights of the program, BP was obtained by ambulatory monitoring. After a 10-min rest, 3 BP and heart rate (HR) recordings were taken and the mean values were considered to represent their awake 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 improved since glycemia (212.0+ 91.5 to 140.2+69.1 mg/dl, P<0.03), urine glucose (12.7+11.8 to 8.6+6.4 g/24h, P=0.08) and insulin dose (31.1+7.7 to 16.1+9.7 U/day, P<0.01) were reduced on the 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). Diabetic patients showed a slight decrease in mean BP during the first night. However, the fall in BP during the nocturnal period increased significantly on the eighth night. The average awake-sleep BP variation was significantly higher at the end of the study (4.2 vs 10.3 percent, P<0.05) and this ratio turned out to be similar to that found in the control group (10.3 vs 16.3 percent). HR 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 the normal pattern. We suggest that amelioration of glycemic control may influence the awake-sleep BP and HR differences. This effect may be due at least in part to an attenuated insulin stimulation of sympthetic activity.

Different urinary albumin responses to submaximal exercise by normoalbumin-uric diabetic children and controls

It is not clear if exercise could be useful to identify diabetic patients at risk for the development of nephropathy. We evaluated the responses of blood pressure (BP) and urinary albumin (Alb) and retinol-binding protein (RBP) excretion to standardized sub-maximal exercise in 17 normoalbuminuric normotensive children with IDDM and 17 matched normal subjects. RBP was used as an index of tubular function. Standardization of exercise load was based on heart rate (HR) which was maintained at 70 per cent of the maximum calculated to age. A step exercise test lasted for 35 min; baseline BP and HR were taken at midtime and during cooling down. Pre- and postexercise urines were obtained for Alb, RBP and creatinine determinations. Both groups showed a significantly increased systolic BP at the midpoint but the percent variations were not different. HR responses did not differ and demonstrated the exercise effectiveness. Great variability in Alb excretion was observed within the normal range for both groups. The baseline Alb/creatinine ratio was not significantly different between normal and diabetic subjects, but became different following exercise (6.6 ñ 4.1 vs 17.7 ñ 18.7 mg/g, P<0.05). While this ratio decreased in the control group (14.8 ñ 11.1 to 6.6 ñ 4.1 mg/g, P<0.02), it increased (9.0 ñ 7.1 to 17.7 ñ 18.7 mg/g, P = 0.05) in diabetic patients. Percent variations in the two groups occurred in opposite directions and were significantly different. RBP/creatinine followed the same pattern within each group; normals showed a tendency to a decrease (0.058 ñ 0.064 to 0.030 ñ 0.039 mug/g, P = 0.05) and diabetic patients to an increase (0.116 ñ 0.125 to 0.247 ñ 0.247 mug/g, P = 0.06). We conclude that there was a variable proteinuric response to exercise among diabetic subjects with normal renal function as evaluated by albumin excretion. A subset of IDDM patients responded abnormally to the exercise stress, increasing albumin excretion to levels compatible with microalbuminuria. Whether this heterogeneity reflects individual risk for diabetic renal disease requires further investigation.