WEDNESDAY, June 2 (HealthDay News) -- In people with pre-diabetes, a low-dose combination of two diabetes drugs -- metformin and Avandia (rosiglitazone) -- appeared to reduce the progression to type 2 diabetes, new research shows.

The study found that the risk of developing type 2 diabetes was reduced by two-thirds in those taking the drug combo compared to those on placebo.

"Diabetes is a complex metabolic disorder, and it's unlikely that there will ever be one magic bullet that treats or prevents diabetes," explained study author Dr. Bernard Zinman, director of the Leadership Sinai Centre for Diabetes at Mount Sinai Hospital and the University of Toronto. "So, more like treatments for HIV/AIDS or cancer that use a drug cocktail, we attempted to look at two drugs that have been known to have beneficial effects in diabetes."

"We were pleasantly surprised to find that using half of the maximum dose was extremely effective for preventing type 2 diabetes," he said.

In addition, Zinman said that the drug combination appeared to counteract the weight gain that's common with Avandia therapy alone. He said that the researchers saw very few side effects in this study.

One major concern about this drug combination, however, is in the use of Avandia. This medication has come under intense FDA scrutiny because it has been associated with an increased risk of heart failure and heart attack. Prescribing information for Avandia now carries a warning that the drug is not recommended for use in anyone with symptomatic heart disease, and that evidence linking the drug with an increased risk of heart attack is still inconclusive.

Zinman said that although this study wasn't designed to assess the safety of Avandia, they didn't see an increase in the risk of cardiovascular disease. He also pointed out that this study used only half of the FDA-approved starting dose of the drug.

Findings from the study, which was funded by Avandia's maker, GlaxoSmithKline, were published in the June 3 online edition of The Lancet.

The trial included 207 adults with impaired glucose tolerance, sometimes called pre-diabetes. Not everyone with impaired glucose tolerance goes on to develop type 2 diabetes, but the condition is associated with long-term cardiovascular risks, according to Dr. Richard Bergenstal, president of medicine and science for the American Diabetes Association.

"Impaired glucose tolerance, although not labeled a disease, is not a benign condition," he said.

The current gold standard of treatment for pre-diabetes, according to Bergenstal, is lifestyle changes such as getting regular exercise and losing weight. And, when maintained, lifestyle changes can be very effective in preventing type 2 diabetes, but such changes aren't always maintained.

"Lifestyle changes have to be the basis for treating diabetes," concurred Zinman, "But, the number of people who implement those changes effectively is small. For someone to lose weight and maintain that weight loss is uncommon."

The study included a year of structured lifestyle intervention for all of the study volunteers. In addition, 103 study participants were given 2 milligrams (mg) of Avandia once a day and 500 mg of metformin twice daily, while 104 people were given placebo pills.

The average follow-up time was 3.9 years, and during that time 14 percent of the drug combo group developed type 2 diabetes, while 39 percent of the placebo group did.

That translates to a 66 percent reduced risk of progressing to diabetes for the treatment group, according to the study.

Additionally, 80 percent of those treated achieved normal blood sugar levels during the study compared to just 53 percent in the placebo group.

"It's critically important that we stem this epidemic of diabetes and we need to start in pre-diabetes. Lifestyle changes can be very effective, and we're gaining more information about which medications or combinations of medications can be helpful in addition to lifestyle changes," said Bergenstal. But, he added, it's not clear from this one small study if this drug combination can truly prevent the progression of pre-diabetes to type 2 diabetes.

More information

To learn more about pre-diabetes and what you can do to prevent type 2 diabetes, visit the American Diabetes Association.