Changes in Blood Pressure and Renal Function in Patients with Type I (insulin-dependent) Diabetes Mellitus Prior to Clinical Diabetic Nephropathy

58 type I (insulin-dependent) diabetic patients who in the period 1975 to 1981 developed clinical diabetic nephropathy (urinary protein excretion greater than 0.5 g/day) (group I) were matched in pairs to 58 patients not developing nephropathy (group II) according to sex (29 males and 29 females), age (33 years (18-46) vs. 33 years (15-48] and diabetes duration (19 years (6-39) vs. 19 years (6-42]. Supine blood pressure measured during hospitalization and weight X 100/serum creatinine were evaluated as to diabetes duration in the periods greater than 10, 10-6, 5-1 years prior to and at the onset of proteinuria. There was no difference in initial blood pressure (124/78 +/- 11/10 mmHg (group I) vs. 125/79 +/- 11/10 mmHg (group II]. Diastolic blood pressure was higher from 10-6 (85 +/- 9 vs. 80 +/- 7 mmHg; p less than 0.05) and systolic blood pressure from 5-1 (138 +/- 17 vs. 129 +/- 17 mmHg; p less than 0.01) years before onset of proteinuria in group I compared with group II. There was no difference in weight X 100/serum creatinine initially (87 +/- 17 kg/mumol/l (group I) vs. 88 +/- 13 kg/mumol/l group II) but from the period 5-1 years prior to the onset proteinuria it was reduced in group I (80 +/- 14 kg/mumol/l vs. group II (86 +/- 14 kg/mumol/l); (p less than 0.05). In conclusion, there was no initial difference in blood pressure and renal function between type I diabetic patients who later developed clinical diabetic nephropathy and those who didn't. Increase in blood pressure starts 5-10 years and renal function impairs 1-5 years before the onset of proteinuria.