Given the additional evidence provided by these three studies, clinicians must be encouraged to make use of these agents Drugs that block the renin-angiotensin-aldosterone system remain underused as a means of preventing renal deterioration in patients with type 2 diabetes, according to an editorial by T.H. Hostetter in the New England Journal of Medicine.
The accumulating evidence on the efficacy of these agents in type 2 diabetes has been bolstered by three new studies. Parving et al showed that the angiotensin-II–receptor blocker irbesartan had a renoprotective effect that was independent of its effect on blood pressure in patients with type 2 diabetes, hypertension, and microalbuminuria. Glomerular filtration rates were normal at the beginning of the study, and 2 years later diabetic nephropathy (urinary albumin excretion rate >200 μg/min or at least 30% higher than baseline) had developed in 5.2% of patients receiving 300 mg a day of irbesartan and in 14.9% of controls.
Lewis et al compared irbesartan (300 mg a day) with the calcium channel blocker amlopidine (10 mg a day) and placebo in patients with type 2 diabetes and established nephropathy. In a similar group of patients, Brenner et al compared the angiotensin-II–receptor blocker losartan (50 to 100 mg a day) with placebo in a similar group of patients who were also taking conventional antihypertensive therapy.
In both studies, patients taking the angiotensin-II–receptor blocker had lower levels of proteinuria, lower rates of decline in the glomerular filtration rate, and later onset (about 2 years) of end-stage renal disease.
Unfortunately, these studies did not address the effects of angiotensin-II–receptor blockers in Hispanic, black, and Native American patients, in whom the risk of end-stage renal disease is particularly high. For example, a recent study indicated that the ameliorating effect of angiotensin-converting enzyme (ACE) inhibitors on left ventricular dysfunction is less in black patients than in white patients.
However, the African American Study of Kidney Disease and Hypertension did show that an ACE inhibitor was more effective in mitigating the progression of renal disease than a calcium channel blocker. Thus, blockade of the renin-angiotensin-aldosterone system appears to be prudent for these patients as well, said Hostetter.
Given the additional evidence provided by these three studies, clinicians must be encouraged to make use of these agents, he said.
Hostetter TH. Prevention of end-stage renal disease due to type 2 diabetes [editorial]. N Engl J Med.