Longitudinal evaluation of renal function in non-insulin-dependent diabetic patients with early nephropathy: effects of angiotensin-converting enzyme inhibition.

A prospective self-controlled evaluation of renal function in non-insulin-dependent diabetic patients with early nephropathy, mild to moderate hypertension, and retinopathy was undertaken over a 1-year period. Thereafter, the effects of treatment with captopril on blood pressure, albumin excretion, and renal function were assessed. Glomerular filtration rate (GFR), effective renal plasma flow (ERPF), and systolic and diastolic blood pressures remained stable during the pretreatment period; 24-h urinary protein excretion increased progressively from 0.79 +/- 0.13 to 1.23 +/- 0.18 g/24 h (p < 0.05) (mean +/- standard error). Captopril (25 mg b.i.d.) for 3 months reduced systolic and diastolic blood pressures significantly (p < 0.01). Simultaneously, 24-h urinary protein excretion declined by 41 +/- 2.4%, to 0.70 +/- 0.12 g/24 h (p < 0.05) while GFR, ERPF, and fractional filtration demonstrated small but insignificant changes. Subsequently, increase in captopril to 50 mg b.i.d. for the remaining 6 months did not produce further significant changes in renal hemodynamics, blood pressure, or urinary protein excretion (0.48 +/- 0.10 g/24 h at the termination of the study). Non-insulin-dependent diabetic patients with early nephropathy and mild to moderate hypertension demonstrate a progressive increase in urinary protein excretion. Administration of captopril resulted in prompt control of hypertension and reversal of the increase in urinary protein excretion.