Effect of captopril on blood pressure and kidney function in normotensive insulin dependent diabetics with nephropathy.

OBJECTIVE--To assess whether inhibition of angiotensin converting enzyme protects kidney function in diabetic nephropathy. DESIGN--Open, randomised follow up study of normotensive insulin dependent diabetics with nephropathy either treated or not with captopril for one year. SETTING--Outpatient diabetic clinic in a tertiary referral centre. PATIENTS--32 Normotensive patients with insulin dependent diabetes complicated by nephropathy who were randomised either to the treatment group (n = 15) or to the control group (n = 17). INTERVENTIONS--The treatment group was given captopril (25-100 mg/day) for 12 months, the average dose during the second six months of the study being 40 mg daily. Controls were not treated. MAIN OUTCOME MEASURES--Albuminuria, arterial blood pressure, and the glomerular filtration rate. RESULTS--Mean arterial blood pressure fell by 3 (SE 2) mm Hg in the captopril treated group and rose by 6 (1) mm Hg in the controls. In addition, albuminuria declined by 11% in the captopril treated group and rose by 55% in the controls, fractional albumin clearance fell by 17% in the captopril treated group and increased by 66% in the controls, and the glomerular filtration rate declined by 3.1 (2.8)ml/min/1.73 m2 with captopril and by 6.4 (3.1) ml/min/1.73 m2 in the controls. CONCLUSION--Inhibition of angiotensin converting enzyme arrests the progressive rise in albuminuria in normotensive insulin dependent diabetics with nephropathy.