Effects of captopril treatment versus placebo on renal function in type 2 diabetic patients with microalbuminuria: a long-term study

We evaluated the renal effect of long-term antihypertensive treatment (12 months) with the angiotensin-converting enzyme inhibitor captopril compared to placebo in 15 type 2 diabetic patients with microalbuminuria. The patients were randomly allocated to captopril (n = 9) or placebo (n = 6). After 1-year therapy no significant decrease in blood pressure was demonstrated with captopril (139 ± 17/80 ± 9 versus 138±13/76±6 mmHg) or placebo (138 ± 9/75 ± 6 versus 135 ± 14/79 ±10 mmHg). Only in a small hypertensive subgroup (n = 4) treated with captopril did we find a significant reduction in blood pressure (154 ± 2/88 ± 1 versus 142 ± 7/78 ± 5 mmHg,P < 0.05). The urinary albumin excretion rate did not change significantly either in the captopril group (95.6 mg/24 h, 25th percentile 138.4, 75th percentile 25.1; versus 127.8 mg/24 h, 25th percentile 29.3, 75th percentile 222) or in the placebo group (99.2 mg/24 h, 25th percentile 58.5, 75th percentile 125.8; versus 120.9 mg/24 h, 25th percentile 62.1, 75th percentile 179.7). There were also no alterations in renal blood flow or filtration rate. In the hypertensive subgroup treated with captopril a reduction in urinary albumin excretion rate after 3 and 6 months of treatment was observed (captopril 73.4 versus 24 and 41 mg/24 h,P < 0.05), but not after 12 months. Triglyceride and cholesterol levels remained constant before and after treatment while glycosylated hemoglobin decreased significantly after 12 months captopril (7.8 ± 0.9 versus 6.9 ± 0.7 mg%,P < 0.03). We conclude that in patients with type 2 diabetes with microalbuminuria angiotensin-converting enzyme inhibitors may have protective renal effects in so far as a lack of increase in urinary albumin excretion is equivalent to low progression in renal disease.