Short term effect of captopril on microalbuminuria induced by exercise in normotensive diabetics

Abstract

Objective: To investigate whether captopril has any effect on microalbuminuria induced by exercise in normotensive diabetic patients with early stage nephropathy.

Design: Randomised, double blind, crossover trial.

Setting: Outpatient department.

Patients: 22 diabetics with stage II nephropathy (urinary albumin excretion rate less than 20 micrograms/min; 15 with type I diabetes and seven with type II), 32 patients with stage III nephropathy (urinary albumin excretion rate 20-200 micrograms/min; 14 with type I diabetes and 18 with type II), and 10 normal subjects.

Interventions: Four exercise tests on a cycle ergometer: the first two under basal conditions and the third and fourth after subjects had received captopril (two 25 mg doses in 24 hours) or placebo (two tablets in 24 hours).

End point: Exercised until 90% of maximum heart rate achieved.

Measurements and main results: Mean urinary excretion one hour after the first two exercise tests was 21 micrograms/min in normal subjects, 101 micrograms/min in diabetic patients with stage II nephropathy, and 333 micrograms/min in those with stage III nephropathy. Similar results were obtained after placebo. After captopril the urinary excretion rate one hour after exercise was significantly decreased in diabetics with stage II (36 micrograms/min) and stage III (107 micrograms/min) disease compared with placebo but not in normal subjects. Systolic and diastolic pressures were similar in the three groups after placebo and captopril had been given.

Conclusions: Captopril significantly reduces microalbuminuria induced by exercise in normotensive diabetics without affecting systemic blood pressure. Captopril may reduce renal intracapillary pressure.