It determined that patients who had taken the drugs such as Metformin, originally marketed as Glucophage, were much less likely to have lung cancer spread.
Metformin, which is an older and cheaper drug than the newer drugs such as Avandia and Actos, had a more powerful effect.
Scientists say it may be possible one day to use Metformin to prevent lung cancers in smokers.
Metformin is one of the most widely used drugs for type 2 diabetes.
