Captopril in patients with type II diabetes and renal insufficiency: systemic and renal hemodynamic alterations

To our knowledge, clinical studies on the long-term use of angiotensin converting enzyme inhibitors in patients with type II diabetes mellitus and nephropathy with incipient renal failure are nonexistent. We therefore assessed the effects of long-term treatment with captopril on systemic and renal hemodynamics and urinary protein excretion in patients with type II diabetes mellitus and the clinical syndrome of diabetic nephropathy.

Twelve patients, 10 men and two women, with an average age of 52 years (range, 40 to 66), participated in the study. After the basal hemodynamic evaluation, the patients received captopril in two daily doses. The dosage was adjusted at weekly intervals in order to obtain normalization of blood pressure without exceeding the maximum allowable dosage. Four patients also received furosemide (20 to 40 mg/day).

After six months of treatment, the intra-arterial blood pressure fell (from 162 +/- 17/103 +/- 5 to 139 +/- 26/89 +/- 10 mm Hg) due to the reduction in total peripheral vascular resistance index (from 3,720 +/- 658 to 3,190 +/- 762 dynes/second/cm-5/m2), with no change in cardiac index (2.78 +/- 0.36 to 2.79 +/- 0.47 liters/minute/m2). No significant change was seen in renal vascular resistance (from 30,175 +/- 5,371 to 30,173 +/- 5,372 dynes/second/cm-5/1.73 m2) and in filtration fraction (from 26 +/- 8 to 27 +/- 10 percent). A slight, not significant, decrease in renal plasma flow (from 243 +/- 97 to 217 +/- 108 ml/minute/1.73 m2), in glomerular filtration rate (from 57 +/- 17 to 51 +/- 19 ml/minute/1.73 m2), and in proteinuria (from 4.50 +/- 3.10 to 3.40 +/- 2.31 g/day) was also observed.

Our findings suggest that captopril is an effective antihypertensive agent in patients with diabetic nephropathy, but the renal beneficial effects seem to be limited when this syndrome is complicated by renal insufficiency.