Question: In patients with type 2 diabetes mellitus, hypertension, and persistent microalbuminuria, what is the effectiveness of the angiotensin-II–receptor antagonist (ARA) irbesartan for delaying or preventing the development of nephropathy?
Design: Randomized {allocation concealed*}†, blinded {clinicians, patients, and outcome assessors}†,* placebo-controlled trial with 2-year follow-up.
Setting: 96 centers worldwide.
Patients: 611 patients between 30 and 70 years of age who had type 2 diabetes; hypertension defined as systolic blood pressure > 135 mm Hg or diastolic blood pressure > 85 mg Hg or both; persistent microalbuminuria defined as an albumin excretion rate of 20 to 200 µg/min; and a serum creatinine level ≤ 133 µmol/L for men or ≤ 97 µmol/L for women.‡ Exclusion criteria were nondiabetic kidney disease, cancer, fatal disease, or indication for angiotensin-converting enzyme (ACE) inhibitors or ARAs. 590 of 611 (97%) patients (mean age 58 y, 68% men) completed follow-up.
Intervention: Patients were allocated to receive irbesartan, 150 mg/d (n = 195) or 300 mg/d (n = 194), or placebo (n = 201). Patients were treated with antihypertensive drugs as needed, but ACE inhibitors were not allowed. Patients continued their usual diabetes care. Dietary salt and protein were not restricted.
Main outcome measure: Development of nephropathy, defined by a urinary albumin excretion rate > 200 µg/min that is at least 30% higher than the baseline rate.
Main results: Analysis was by intention to treat. At 2 years, unadjusted analyses showed that placebo was associated with a higher incidence of progression to nephropathy than was irbesartan, 300 mg/d (P < 0.001), but not irbesartan, 150 mg/d (P = 0.08). After adjusting for baseline microalbuminuria and blood pressure during the study, placebo was associated with a higher incidence of progression to nephropathy than was irbesartan, 300 mg/d (P < 0.001), and irbesartan, 150 mg/d (P = 0.05) (Table).
Conclusion: In patients with type 2 diabetes mellitus, hypertension, and persistent microalbuminuria, irbesartan delayed progression to nephropathy independent of its effect on blood pressure.
Irbesartan vs placebo for progression to nephropathy in type 2 diabetes, hypertension, and persistent microalbuminuria at 2 years§
| Irbesartan dose | Irbesartan | Placebo | Adjusted hazard ratio (95% CI) | NNT (CI) |
| 150 mg/d | 9.7% | 14.9% | 0.56 (0.31 to 0.99) | 16 (10 to 728) |
| 300 mg/d | 5.2% | 14.9% | 0.32 (0.15 to 0.65) | 11 (8 to 21) |