People on cholesterol-lowering statins are nine percent more likely to develop diabetes but this small absolute risk is outweighed by the drugs' heart-protecting properties, researchers have said.
The finding could prompt a rethink among those with low cardiovascular risk factors who are tempted to take statins to prevent future heart disease.
Experts said the latest finding, published in the Lancet medical journal, should not stop patients at moderate or high heart risk from taking statins. But it could deter a headlong rush to use them even more widely.
"It will stop us putting statins in the water, as it were, and mean we give them when appropriate for the right reasons," lead researcher Naveed Sattar of the Glasgow Cardiovascular Research Centre at the University of Glasgow told Reuters.
Past trials of statins have produced conflicting results, with some - including an influential study of Crestor in 2008 - suggesting they may cause type 2 diabetes, but others pointing to an actual reduction in risk.
To resolve the issue, Sattar and colleagues carried out what is known as a meta-analysis, reviewing data from 13 large gold standard trials of statins between 1994 and 2009, involving more than 91 000 patients.
The result showed the statin-diabetes link was real. But the effect was slight and treating 255 patients with statins for four years would result in only one extra case of diabetes.
For comparison, the researchers estimated that giving statins to the same group would avoid 5.4 deaths or heart attacks over four years, and nearly the same number of strokes or artery-opening procedures would also be avoided.
"Whilst a new risk of statins has been identified, the risk seems small and far outweighed by the benefits of this life-saving class of drugs," Christopher Cannon of Boston's Brigham and Women's Hospital and Harvard Medical School said in an accompanying commentary.
Sattar said the effect appeared to be common to all drugs in the statin class, although whether some may be more detrimental than others required further research.
The diabetes finding contrasts with that of cancer, where another meta-analysis two years ago concluded statins neither caused nor prevented the disease.
Just why statins should be linked to diabetes risk is unclear and cannot be explained by the fact that people on the drugs live slightly longer.
Sattar said the fact that statins cut bad cholesterol, improved blood vessel function and dampened inflammation made the link surprising. But he noted they also affected the liver and muscles, which seemed to tip the balance. - (Reuters, February 2010)