It doesn't even make sense to study Avandia more. "It appears
questionable whether new studies with rosiglitazone will be ethical
given the fact that less dangerous therapeutic alternatives exist."
Since weight is such a big issue to people with diabetes, the clinical studies of all diabetes drugs look at it. But the drug’s ability to reduce our blood glucose levels, as measured by a drop in A1C, is what interests the researchers the most.
In this respect Avandia works quite well. People in a 26-week clinical trial were able to bring down their A1C by 1.5 percent more than those taking a placebo.
But some other drugs that don’t lead to weight gain also improve our A1C even more than Avandia does. Metformin, which is now a generic drug and is also sold under the Glucophage brand, typically reduced A1C by 1.8 percent in a 29 week trial.
Januvia didn’t do as well, bringing down A1C just 0.8 percent more than those on a placebo in 24 weeks. Byetta also reduces A1C, although the only published studies so far show the results when used with another diabetes drug. Amylin Pharmaceuticals tells me that studies of Byetta used alone are due out at the end of the year.
Importantly, none of these drugs – metformin, Januvia, or Byetta – lead to weight gain. Januvia and Byetta are new on the market, but metformin has been available since 1995, even longer than Avandia, which the Food and Drug Administration approved in 1999.
Some people avoid taking metformin because it might cause a rare but dangerous side effect called lactic acidosis, the buildup of lactic acid in the blood. So doctors don’t prescribe it to people who have moderate kidney disease or heart failure.
However, another new study questions the basis of this concern about lactic acidosis from taking metformin. The Annals of Internal Medicine will publish this study in September, but it’s already online.
The federal Agency for Healthcare Research and Quality commissioned this analysis of diabetes drugs in 2005. Its goal was to do the first in-depth comparison of the many oral medications that came out in the previous decade, as well as the sulfonylureas, which been available for half a century. The report didn’t evaluate insulin or other injected diabetes drugs like Byetta.
A key finding of this report is that they found no “evidence of an elevated risk for lactic acidosis in patients taking metformin compared with other oral diabetes agents.” The evidence for metformin-induced lactic acidosis stems mainly from about 300 case reports. “We suspect that apparent cases of ‘metformin-induced lactic acidosis’ may have been overreported,” because an earlier drug in the same class, phenformin, unequivocally did cause lactic acidosis.
Aside from this concern, metformin appears remarkably safe and effective in reducing blood glucose. It certainly doesn’t cause weight gain, and may in fact lead to a little weight loss. It is even much less expensive than Avandia.
