The effect of continuous subcutaneous insulin infusion on renal function in type I diabetic patients with and without proteinuria.

The effect of continuous subcutaneous insulin infusion on renal function was studied in 12 patients with insulin-dependent diabetes mellitus. Serum creatinine was less than 110 mumol/L in all patients. Total urinary protein excretion was less than 250 mg/24 hr in seven patients (group I) and exceeded 0.5 g/24 hr in five (group II). Initial glomerular filtration rate was higher in group I compared with group II: 136.0 +/- 8.5 ml/min versus 103.2 +/- 4.6 ml/min (mean +/- SEM; p less than 0.02). After one to three months pump therapy glomerular filtration rate decreased in both groups. It remained stable during 32-36 months in group I (126.3 +/- 6.1, and 127.9 +/- 7.7 ml/min, respectively) but deteriorated in group II (98.6 +/- 4.4, and 60.0 +/- 6.8 ml/min, respectively; p less than 0.01 compared with group I). These results indicate that strict blood glucose control with continuous subcutaneous insulin infusion does not prevent deterioration of renal function in type I diabetic patients with clinical proteinuria. This suggests that other factors than metabolic control are involved in the course of diabetic nephropathy.