Low doses of metformin and rosiglitazone seem to delay the onset of type 2 in prediabetic people who have impaired glucose tolerance, according to a Canadian study. However, although the drug combination was effective over the first year of the study in helping to control glucose levels and insulin resistance, it was not effective subsequently in delaying the onset of insulin resistance and pancreatic beta cell deterioration.
The study at Mount Sinai Hospital in Toronto tracked 207 participants who had prediabetes. They were divided into two groups, one that received the metformin/rosiglitazone combination and another that received a placebo.
Metformin, one of the oldest, cheapest, and most effective drugs in the arsenal of diabetes medications, is often prescribed to people with prediabetes in an attempt to thwart the onset of type 2. It is often used in combination with other drugs to treat the actual disease.
Rosiglitazone, which belongs to the thiazolidinedione class of drugs, works by binding to receptors in fat cells and making them more receptive to insulin. In the U.S. market, GlaxoSmithKline sells it as a stand-alone drug, under the brand name Avandia, and in combination with metformin as Avandamet.
The researchers concluded that while the drug combination delays the onset of type 2, it cannot prevent what seems to be an inevitable decline in beta cell functioning and insulin sensitivity over time.
(GlaxoSmithKline funded the study and provided the medications used in it. An abstract of the study is available online.)