Comparative effects of Irbesartan on ambulatory and office blood pressure: a substudy of ambulatory blood pressure from the Irbesartan in Patients with Type 2 Diabetes and Microalbuminuria study

OBJECTIVE: Irbesartan was renoprotective independently of its blood pressure-lowering effect in the Irbesartan in Patients With Type 2 Diabetes and Microalbuminuria (IRMA2) study. However, blood pressure was evaluated by trough office blood pressure (OBP), which may underestimate reductions in 24-h ambulatory blood pressure (ABP). In the present study, we evaluated 24-h blood pressure patterns in a subpopulation of the IRMA2 trial.

RESEARCH DESIGN AND METHODS: Type 2 diabetic patients (n = 43) with persistent microalbuminuria (as determined by repeated overnight measurements of urinary albumin excretion [UAE]) and hypertension who were included in the IRMA2 study at the Steno Diabetes Center were subjected to 24-h ABP (Takeda, TM2420) measurements before and 2 years after randomization to placebo (n = 15), irbesartan 150 mg daily (Irb150; n = 13), or irbesartan 300 mg daily (Irb300; n = 15).

RESULTS: At baseline, the placebo, Irb150, and Irb300 groups were comparable: OBP: 157 +/- 15/89 +/- 7, 156 +/-15/91 +/- 11, and 159 +/- 16/90 +/- 9 mmHg (NS); 24-h ABP: 148 +/- 13/83 +/- 11, 148 +/- 16/82 +/- 7 and 147 +/- 16/81 +/- 10 mmHg (NS); and UAE (geometric mean with 95% CI): 43 (32-57), 46 (30-70), and 59 (42-85) micro g/min (NS), respectively. We found that 2 years after randomization, OBP was significantly reduced in all three groups (by 11/7, 13/8, and 13/8 mmHg in the placebo, Irb150, and Irb300 groups, respectively), but that there were no significant differences among groups. Reductions in 24-h ABP were similar in the three groups (11/10, 5/7, and 7/8 mmHg, respectively; NS), as were reductions in day ABP (11/9, 7/7, and 8/9 mmHg, respectively; NS) and night ABP (4/11, 7/7, and 3/3 mmHg, respectively; NS). The reduction in UAE at the end of the study was 0% (-86 to 42), 38% (-14 to 66), and 73% (59 to 82), respectively (overall, P < 0.01).

CONCLUSION: Irbesartan is renoprotective independently of its beneficial effect in lowering 24-h blood pressure in patients with type 2 diabetes and persistent microalbuminuria.