THURSDAY, Sept. 25 (HealthDay News) -- New studies published this week in the The Lancet provide further evidence that candesartan, a blood pressure medicine, can cut the risk and severity of retinopathy in people who have diabetes.

"We suggest that clinicians may wish to consider using candesartan [brand name Atacand] in people with type 1 diabetes with hard-to-control blood glucose, who do not currently have retinopathy," said one study's British co-author, Dr. Nish Chaturvedi, of the National Heart and Lung Institute and Imperial College at St Mary's, London. "In type 2 diabetes, in people with established retinopathy who become hypertensive, again the clinician may wish to consider candesartan from the many blood pressure-lowering agents available, as it appears to have this additional beneficial effect on regression of retinopathy."

About 95 percent of diabetics suffer from type 2 diabetes, where cells gradually lose sensitivity to insulin. The illness is often linked to obesity. Around 5 percent of diabetics have the type 1 form, a condition in which the pancreas is unable to produce insulin to regulate blood sugar.

Diabetic retinopathy is a potentially blinding illness linked to changes in retinal blood vessels. It is one of the major complications of both type 1 and type 2 diabetes. Intense control of blood sugar levels is the only proven way to reduce incidence and progression of retinopathy, but this kind of control can be elusive. And even when patients do achieve strict control of blood sugars, retinopathy is not always kept at bay.

Previous studies have indicated that drugs known as renin-angiotensin system blockers, which include candesartan, might prevent or reduce the severity of diabetic retinopathy.

This most current research consists of two trials, with three arms total.

In the DIRECT-Prevent 1 study, more than 1,400 type 1 diabetics with existing retinopathy were randomized to receive either Atacand or a placebo; in the DIRECT-Protect 1 trial, more than 1,900 type-1 diabetics with existing retinopathy were randomized to receive either the drug or a placebo.

Individuals receiving Atacand had an 18 percent lower incidence of retinopathy, considered "borderline" statistically significant, the researchers report.

Further analysis of the DIRECT-Protect 1 trial found that progression of retinopathy was 35 percent lower for patients taking Atacand.

Reanalyzing the data in this way somewhat weakens the findings, noted one expert, Dr. Mina Chung, a retinal specialist at the University of Rochester's Eye Institute. Nevertheless, she added, "this study gives you some evidence that it looks like [Atacand] would be helpful."

The DIRECT-Protect 2 study randomized more than 1,900 type 2 diabetes patients with mild to moderately severe retinopathy to either Atacand or a placebo.

Again, the difference in progression between the groups was statistically nonsignificant. Improvement increased by 34 percent in the Atacand group versus the placebo group.

"Studies have shown that intensive control of blood-sugar levels helps prevent diabetic retinopathy, and now this is another component of the blood pressure effect, but it may also be additional benefits other than just controlling blood pressure," said Dr. Richard W. Allinson, assistant professor of surgery with the Texas A&M Health Science Center College of Medicine and an ophthalmologist at the Scott & White Waco Clinic.

The trials were funded by AstraZeneca and Takeda. AstraZeneca markets Atacand under license from Takeda.

More information

There's more on diabetic retinopathy at the National Eye Institute.