Protection of kidney function and decrease in albuminuria by captopril in insulin dependent diabetics with nephropathy.

STUDY OBJECTIVE

To assess whether long term inhibition of angiotensin converting enzyme with captopril and frusemide or bendrofluazide protects kidney function in diabetic nephropathy.

DESIGN

Non-randomised controlled before-after trial of matched hypertensive insulin dependent diabetics with nephropathy treated with captopril and frusemide or bendrofluazide.

SETTING

Outpatient diabetic clinic in tertiary referral centre.

PATIENTS

Treatment group of 18 hypertensive insulin dependent diabetics with nephropathy (mean age 33), who had not been treated previously. Control group of 13 patients (mean age 32) fulfilling the same entry criteria from a prospective study.

INTERVENTIONS

Treatment group was given daily captopril 37.5-100.0 mg and frusemide (mean) 98 mg (10 patients) or bendrofluazide (mean) 4 mg (seven). Treatment was continued for about two and a half years. Controls were not treated.

END POINT

Measurement of arterial blood pressure, albuminuria, and glomerular filtration.

MEASUREMENTS AND MAIN RESULTS

Baseline values were identical in treated and untreated groups respectively: mean blood pressure 146/93 (SE 3/1) mm Hg v 137/95 (2/1) mm Hg; geometric mean albuminuria 982 (antilog SE 1.2) micrograms/min v 936 (1.2) micrograms/min; and mean glomerular filtration rate 98 (SE 5) ml/min/1.73 m2 v 96 (6) ml/min/1.73 m2. Mean arterial blood pressure fell by 8.7 (1.3) mm Hg with captopril and rose by 6.6 (1.5) mm Hg in controls, (p less than 0.001); Albumin excretion decreased to 390 (1.1) micrograms/min with captopril and rose to 1367 (1.3) micrograms/min in controls (p less than 0.001). The rate of decrease in glomerular filtration rate was lower with captopril (5.8 (0.7) ml/year v 10.0 (1.3) ml/year) (p less than 0.01). Rate of fall in glomerular filtration rate and mean arterial blood pressure were significantly correlated (n = 31, r = 0.37, p less than 0.05).

CONCLUSIONS

Captopril is a valuable new drug for treating hypertension in insulin dependent diabetics with nephropathy.