American medical researchers say they are stunned by the results of a major government study on diabetes and heart disease. They hoped to prove that a long-trusted form of treatment for lowering blood sugar would, if increased, yield even greater results. But as VOA's Robert Raffaele explains, the study has raised more questions.

A diabetic monitoring her blood glucose levels

U.S. government researchers have curtailed part of a major clinical trial on the treatment of diabetics, especially those at greatest risk.

The reason: study coordinators found that aggressively lowering blood sugar as close as possible to "normal" levels appeared to increase the risk of a fatal heart attack or stroke.

The study focused on 10,000 adults with Type 2 diabetes, the most common form of the disease. The subjects also had cardiovascular disease or at least two contributing risk factors.

The National Institutes of Health halted the study 18 months early after recording 257 deaths among aggressively treated patients, compared to 203 fatalities among those given more standard care.

The results suggested exactly the opposite of what researchers had hoped to prove: that pushing blood-sugar levels below current targets in high-risk diabetics would be beneficial.

Researchers were unable to determine why those treated aggressively had a higher death rate. They found no link between the deaths and the drugs used in the trial, including Avandia, a drug suspected of increasing diabetics' risk of heart attacks.

Despite the uncertainty created by the trial, researchers say diabetics who control their blood sugar can reduce their risk for kidney disease, blindness, and complications leading to amputations.

They say patients should still consult with their doctors before considering any change in treatment.