The drug "significantly" increases the chances of a heart attack, especially during the first year of use. Other studies have put the risk as high as 43 per cent.
Despite these concerns, America's drug regulator, the Food and Drug Administration (FDA), has refused to withdraw the drug, and has instead merely insisted on a 'black box' warning on the drug's packaging.
Their decision was almost a unanimous one, with 22 votes in favour against just 1 - made by the very same people who astonishingly had agreed moments earlier, by 20 votes to 3, that the drug increased the risk of heart disease.
The new study, which involved 14,291 diabetes patients who were either taking the drug or some other control therapy, makes their decision even more perplexing than it originally was.
(Source: Journal of the American Medical Association, 2007; 298: 1189-95).