Certain antihypertensive medications could be used to slow the progression of diabetic retinopathy, says a study in the July 2 issue of The New England Journal of Medicine.

Investigators randomly selected 285 normotensive patients with type 1 diabetes to receive Cozaar (losartan, Merck) 100mg q.d., Vasotec (enalapril, Merck) 20mg q.d., or a placebo for five years.

The authors found that participants in the losartan group were 70% less likely to experience diabetic retinopathy progression than those who took a placebo, and participants in the enalapril group were 65% less likely to demonstrate progression compared with those in the placebo group.

Eye care providers should consider prescribing antihypertensive medications to patients with type 1 diabetes to slow the onset and progression of retinopathy, the authors concluded. Yet, the authors remained uncertain as to at what age these patients should start taking antihypertensive drugs or for how long to take them.

The question as to whether or not blocking the renin-angiotensin systems (RAS) prevents small blood vessel complications of diabetes, including diabetic retinopathy (DR), has been with us for some time now, says A. Paul Chous, M.A., O.D., of Tacoma, Wash. Research shows that levels of angiotensin conversion enzyme (ACE) and angiotensin II are elevated in the vitreous and retina of animals and humans with DR, and that these levels rise with increasing severity of retinopathy. So, given this biology, it makes sense that blocking the RAS might prevent or minimize DR.

Whether use of these antihypertensive medications becomes standard practice for minimizing progression of DR remains an open question, Dr. Chous says. Still, ACE inhibitors and angiotensin II receptor blockers do have an excellent safety profile, so it is not improbable that they will be more widely used once patients develop any level of retinopathy.

Mauer M, Zinman B, Gardiner R, et al. Renal and retinal effects of enalapril and losartan in type 1 diabetes. N Engl J Med. 2009 Jul 2;361(1):40-51.