According to the American Diabetes Association, nearly 24 million people in the United States have diabetes, the vast majority of whom have Type 2 diabetes. While this might sound like a huge number — and at 7.8% of the population, it is — it is dwarfed by the number of people who have prediabetes, also called impaired glucose tolerance: 57 million. As the term suggests, most people with prediabetes eventually develop full-blown Type 2 diabetes, and much research has focused on ways to stop this progression.
The latest example of such efforts is a study, published on the Web site of the journal The Lancet, that tested half-doses of metformin (available generically and under brand names Glucophage, Fortamet, Riomet, and others) combined with half-doses of rosiglitazone (brand name Avandia) in 103 people with prediabetes, for an average of about four years. An additional 104 people with prediabetes were given a placebo (inactive pill). At the end of the study, 14% of the combined-drug group had developed diabetes, compared with 39% of the placebo group: a 66% lower rate of developing diabetes. Insulin sensitivity — how responsive the body’s cells are to insulin, as measured by an oral glucose tolerance test — was lower in the placebo group but barely changed in the combined-drug group. The study was funded by the manufacturer of Avandia, GlaxoSmithKline.
In a Reuters article on this research, the study’s leader, Dr. Bernard Zinman of the University of Toronto, stated his belief that either drug in the drug class to which Avandia belongs — called thiazolidinediones — would have an effect like the one found in the study. The other drug, pioglitazone (brand name Actos), is a major competitor of Avandia. Avandia has seen its sales drop sharply in recent years as a result of concerns about its safety: Three years ago, a study found that it increased the risk of heart attack, leading to changes in its warning label and an FDA-ordered trial of its safety that is currently taking place. Dr. Zinman noted that the side effects typically associated with Avandia were not seen in his half-dose study. These include weight gain and fluid retention, which may indicate that someone has an elevated cardiovascular risk. Participants in the combined-drug group did, however, experience a higher incidence of diarrhea than the placebo group; metformin is known for its gastrointestinal side effects.
The combination of Avandia and metformin is not, of course, the only treatment that has been tested for prediabetes. A study completed in 2002, called the Diabetes Prevention Program, compared “lifestyle intervention” — intensive training on diet, exercise, and other behaviors — with both metformin and placebo in people with prediabetes. It found that lifestyle intervention reduced the risk of developing diabetes by 58% compared with placebo; metformin reduced the risk by 31%. Neither metformin alone nor lifestyle changes were compared with the Avandia–metformin combination in the latest study.
What do you think — does this study show that there is still promise for Avandia, or simply that GlaxoSmithKline is interested in selling it? Should other treatments, such as diet and exercise changes or metformin alone, have been included in the study? If you were ever diagnosed with prediabetes, what treatment — if any — did you receive, and were you pleased with the results? Leave a comment below!