Diabetes study finds older drug beats new

December 05, 2006|By Thomas H. Maugh II | Thomas H. Maugh II,Los Angeles Times

The first major head-to-head study comparing the newer diabetes drug Avandia to the older medicines metformin and glyburide shows that Avandia provides better glucose control than metformin but carries more serious side effects and a higher cost, researchers said yesterday.

"Metformin is still the first drug of choice" for newly diagnosed Type 2 diabetes, said the study's leader, Dr. Steven E. Kahn of the University of Washington and the Puget Sound Veterans Affairs Health Care System.

Both Avandia, whose generic name is rosiglitazone, and metformin performed substantially better than glyburide, however.

"People who use glyburide will have to think about changing drugs," he said. "In my opinion, the use of glyburide for any reason other than cost is going to become harder to justify."

Glyburide, a generic sold under the brand names Micronase and Diabeta, among others, is the cheapest of the three drugs. It is still used by some physicians in this country as first-line therapy but is more widely used overseas.

The results of the study were reported yesterday at the 19th World Diabetes Congress in Cape Town, South Africa, and will be published Thursday in The New England Journal of Medicine.

The study was funded by Avandia's manufacturer, GlaxoSmithKline. Kahn reported receiving consulting fees, grants and lecture fees from the company.

The study enrolled 4,360 newly diagnosed diabetics who had never received drug therapy for the disorder. The patients were randomly divided into three groups, each of which received one of the drugs. The main goal of the study was to determine the time until the therapy stopped working and the patients required the addition of a second drug for glucose control.

At the end of five years, 15 percent of patients receiving rosiglitazone needed a second drug, compared with 21 percent of those receiving metformin and 32 percent of those receiving glyburide.

But 62 of the patients taking Avandia developed a heart problem, compared with 58 taking metformin and 41 taking glyburide. A previous study had also shown an apparent increase in heart problems among Avandia users.

Avandia users retained more water than those taking the other drugs and were twice as likely to suffer bone fractures in the hands and feet, especially among women. Those taking Avandia gained 10 pounds over five years compared with a gain of three pounds on glyburide and a loss of six on metformin.

The study design defined failure of a drug to occur when fasting blood glucose levels rose above 180 mg/dl, the standard in use when the study was organized.

More recently, physicians have begun to rely on a different measurement, called glycated hemoglobin, which is a cumulative measure of blood sugar over the past two to three months.

By this assay, the difference between Avandia and metformin - a generic also sold under the brand names Glucophage and Fortamet - was smaller, Dr. David M. Nathan of the Massachusetts General Hospital wrote in an editorial accompanying the NEJM paper.

Given the "modest" benefit of rosiglitazone, he wrote, "metformin remains the logical choice when initiating pharmacotherapy for Type 2 diabetes."

Nathan reported receiving financial support from GlaxoSmithKline for an educational program and grant support from competing companies.

Thomas H. Maugh II writes for the Los Angeles Times.

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