Contrasting effects of enalapril and metoprolol on proteinuria in diabetic nephropathy.

OBJECTIVE

To assess whether angiotensin converting enzyme inhibition reduces proteinuria in diabetic nephropathy more than blood pressure reduction with other antihypertensive treatment.

DESIGN

Prospective, open randomised study lasting eight weeks in patients with diabetic nephropathy.

SETTING

Outpatient nephrology clinics.

PATIENTS

40 Patients with type I diabetes and diabetic nephropathy with reduced renal function.

INTERVENTION

Antihypertensive treatment with enalapril or metoprolol, usually combined with frusemide.

MAIN OUTCOME MEASURES

Arterial blood pressure and urinary excretion of albumin and protein.

RESULTS

Arterial blood pressure after eight weeks was 135/82 (SD 13/7) mm Hg in the group given enalapril and 136/86 (16/12) mm Hg in the group given metoprolol. Proteinuria and albuminuria were similar in both groups before randomisation. After eight weeks' treatment, the geometric mean albumin excretion was 0.7 (95% confidence interval 0.5 to 1.2) g/24 h in the patients given enalapril and 1.6 (1.1 to 2.5) g/24 h in the patients given metoprolol (p less than 0.02). The proteinuria was 1.1 (0.7 to 1.7) and 2.4 (1.6 to 3.6) g/24 h respectively (p less than 0.02).

CONCLUSIONS

Antihypertensive treatment with enalapril reduced proteinuria in patients with diabetic nephropathy more than an equally effective antihypertensive treatment with metoprolol. This points to a specific antiproteinuric effect of the angiotensin converting enzyme inhibitor independent of the effect on systemic blood pressure.