Short-term effect of angiotensin-converting enzyme inhibitor enalapril in incipient diabetic nephropathy.

The short-term effect (2 weeks) of angiotensin-converting enzyme inhibitor (enalapril) on renal hemodynamics and urinary albumin excretion was investigated in eleven normotensive patients with incipient diabetic nephropathy (IDN). Six patients had had elevated baseline glomerular filtration rate (GFR) and each responded to enalapril with a decline in the GFR, from a mean of 160.7 to 134 ml/min/1.73 m2, (p less than 0.05). Their respective filtration fraction values also decreased from a mean of 27.8 to 23.8% (p less than 0.01). Such renal hemodynamic change was accompanied by a decrease in urinary albumin excretion (33 to 19 micrograms/min, p less than 0.05). The remaining 5 patients had displayed normal baseline GFR (mean, 109.6 ml/min/1.73 m2), responded to enalapril with minimal change in the GFR (115.2 ml/min/1.73 m2) and showed no significant improvement in their microalbuminuria. It is concluded that enalapril is effective in lowering glomerular filtration pressure and ameliorating microalbuminuria in the normotensive patient with IDN only when the baseline GFR is elevated.