Blood pressure drugs slow eye damage in diabetics

In a surprise finding, researchers have found that two blood pressure drugs may help prevent diabetes-related eye damage -- even before patients develop symptoms.

The study of the Vasotec brand of enalapril and the Cozaar brand of losartan was originally meant to investigate whether the drugs could slow kidney deterioration in people with type-1 diabetes.

It was hoped the drugs would affect the body's renin-angiotensin system which regulates both renal function as well as blood pressure.

Shortly after the study began, the research team led by Dr. Michael Mauer of the University of Minnesota decided to include evaluations for diabetic retinopathy, an eye condition in which blood vessels in the eyes leak and damage vision.

While the study found the drugs were no better than placebo for preventing kidney damage, they did slow progression of diabetic eye damage in more than 65 per cent of patients.

The researchers followed 285 patients with type 1 diabetes with normal kidney function and normal blood pressure for five years. They found that diabetic retinopathy progressed significantly in 38 per cent of the volunteers getting a placebo compared to only 25 per cent who took enalapril and 21 per cent who got losartan.

The drugs work in different ways to counter the effects of angiotensin, which raises blood pressure by tightening arteries. They are also commonly prescribed to slow diabetes-related kidney damage once damage has started.

It appears that the drugs worked on reducing eye damage not by lowering blood pressure or controlling blood sugar, but by simply inhibiting the renin-angiotensin system.

Mauer said the drugs are not for everyone and can cause birth defects if given to pregnant women.

He added that more research is needed before the drugs could be routinely given to diabetics who show no signs of kidney or eye problems.

But he said for those patients with difficult to control blood sugar who are developing early eye changes, the drugs may offer new promise.

The research appears in the New England Journal of Medicine.