The Irbesartan Microalbuminuria (IRMA)-2 trial59 examined the possibility that an ARB, irbesartan, could delay or prevent the development of clinical proteinuria in patients with type 2 diabetes, microalbuminuria, and a normal serum creatinine level (1.3 mg/dL [114.9 µmol/L] for men and 1.1 mg/dL [97.2 µmol/L] for women). Patients with type 2 diabetes whose overnight albumin excretion rate (UAER) was 20 to 200 µg/min on 2 of 3 consecutive samples were randomized to receive placebo or irbesartan, 150 to 300 mg/d. The blood pressure goal was under 135/85 mm Hg 3 months after randomization; additional antihypertensive agents, except ACE inhibitors and dihydropyridine calcium channel blockers, were allowed to achieve that goal. The primary end point of the trial was defined as the occurrence of a UAER higher than 200 µg/min and/or a UAER at least 30% higher than baseline on at least 2 consecutive measurements. Average blood pressure values were slightly lower in the 2 groups treated with irbesartan than in the placebo group during the first 6 months of the study, but this small difference disappeared during the last 12 months of the study. Subjects were followed for an average of 2 years. In the irbesartan (150 mg/d) group vs placebo, there was a 39% reduction (P = .08 [nonsignificant]) in the development rate of clinical proteinuria, while in the irbesartan (200 mg/d) group there was a 70% reduction in the primary end point (Table 3). Return to a normal UAER, defined as a UAER less than 20 µg/min, was 34% more frequent among patients treated with irbesartan, 300 mg/d, than among patients in the placebo group. The results of this study demonstrate that the ARB irbesartan, 300 mg/d, can delay progression of microalbuminuria to clinical proteinuria in patients with type 2 diabetes.