In type 2 diabetics with microalbuminuria, irbesartan reduces albumin excretion independent of its antihypertensive effect. That, according to the results of a randomized controlled trial reported in the November issue of Diabetes Care.
"Angiotensin-converting enzyme (ACE) inhibitors delay the progression from incipient to overt diabetic nephropathy and reduce albumin excretion rate (AER), independently of blood pressure," write Ferdinando C. Sasso, MD, PhD, and colleagues from the Second University of Naples in Italy. "Irbesartan is a long-acting angiotensin-type 1 receptor antagonist (AT1-RA) with a dose-related action and a good tolerability profile."
Of 124 microalbuminuric type 2 diabetic males enrolled in this study, 64 were hypertensive and 60 were normotensive. The two groups were well-matched for age, body mass index, HbA1c, and diabetes duration. Each group was randomized to treatment with irbesartan, 150 mg twice daily orally, or placebo for 60 days. In a double-blind crossover design, the subgroups who had received placebo were switched to irbesartan after 15 days of washout, and vice versa.
Irbesartan reduced 24-hour mean systolic and diastolic pressure in the hypertensive group and AER in both groups.
"These results indicate the beneficial effects of irbesartan on AER in type 2 diabetic subjects, independently of its antihypertensive effects," the authors write. "The effect of irbesartan on microalbuminuria, even in normotensive type 2 diabetic subjects, suggests that the nephroprotection brought about by AT1-RA could be caused by the direct action on renal hemodynamics and glomerular morphology." Diabetes Care. 2002;25(11):1909-1913