Study co-author JoAnn Manson of the Harvard Medical School said 6.4 percent of women who didn't use statins developed diabetes during the eight to nine years of follow-up, but it rose to 9.9 percent among statin users.
However, the study authors told USA Today that patients should not stop taking their medications without talking to a doctor because statins have been proven to prevent heart attacks and strokes, and that outweighs any potential increase in type 2 diabetes risk.
Nonetheless, the findings that the almost 50 percent increase in diabetes among longtime statin users should dissuade doctors from prescribing statins to healthy people, Manson said.
Since 2008, there have been increased risk of diabetes among statin users, but researchers have said they don't know why the statins have this affect.
The findings were published in the Archives of Internal Medicine.