Ambulatory blood pressure and heart rate in relation to kidney structure and metabolic control in adolescents with Type I diabetes

Aims/hypothesis. To evaluate the relationship between metabolic control, ki dney function, ambulatory blood pressure and renal morphology in normoalbum inuric adolescents with Type I (insulin-dependent) diabetes mellitus. Methods. Metabolic control, clearance of inulin and para-amino hippuric aci d, 24 h ambulatory blood pressure and renal biopsies were studied in 41 pat ients who were 17.8 +/-0.5 (SEM) years of age and 10.7 +/-0.5 years after o nset of diabetes. Results. Glomerular filtration rate and filtration fraction were higher in diabetic patients than in healthy control subjects. At least one third of t he patients had systolic and nocturnal diastolic blood pressures above the 90th centile. Basement membrane thickness was 512 +/- 17 nm, volume fractio n of mesangial matrix 10.7 +/-0.3% and foot process width 415 +/-6 nm. Noct urnal mean arterial blood pressure, adjusted for body height and gender, co rrelated directly to the basement membrane thickness, the volume fraction o f mesangial matrix and the foot process width. Multiple regression analysis showed that HbA(1c), nocturnal heart rate and body height account for 44% of the variations in blood pressure. HbA(1c), nocturnal heart rate and body height explained 57% of the variation in basal membrane thickness, and HbA (1c), nocturnal heart rate and duration of diabetes explained 43% of Vv(mat rix/glom). Actual renal function or urinary albumin excretion rate had no e ffect. Conclusion/interpretation. Nocturnal heart rate and nocturnal blood pressur e, especially the mean arterial blood pressure, seem to be related to glome rulopathy changes in patients in whom persistent microalbuminuria has not y et developed. These findings suggest that a disturbance in sympathovagal ba lance could have a pathogenic effect.