People who are at risk of developing Type 2 diabetes may be able to prevent its onset by taking Avandia, a drug that currently is used for treatment of the disease.

Inability to produce sufficient insulin to regulate glucose levels in the blood results in Type 2 diabetes. It also can be caused by resistance to insulin the body does produce. Many people with precursor conditions that place them at risk are unaware of the problem, because they do not experience any symptoms.

Rising obesity rates triggered by changes in nutrition and exercise habits worldwide have contributed to soaring Type 2 diabetes rates; about 5 percent of all adults currently have the disease. Diabetes can cause blindness, severe kidney damage, circulatory problems and even death.

Researchers investigated whether GlaxoSmithKline's Avandia, which already was being used to treat Type 2 diabetics, would have any effect on two precursors: impaired glucose tolerance and impaired fasting glucose.

The study involved 5,269 adults in 21 countries who had either of the precursor conditions. Each of the volunteers took either a daily 8 mg dose of Avandia or a placebo. Avandia works by reviving the cellular response to insulin, which helps to remove glucose from the blood.

Over the course of the three-year study, participants received regular advice on weight control, exercise and nutrition, which also may have influenced the likelihood of developing diabetes.

By its conclusion, 658 people on the placebo had developed diabetes, but only 280 of those taking Avandia had developed the disease. That works out to more than a 50 percent reduction in diabetes with use of the drug.

Many volunteers in the study also found that Avandia returned their blood sugar function to normal.

Fourteen of the patients taking Avandia and two taking placebos experienced nonfatal heart attacks.