Taking statins significantly increases the risk of developing type 2 diabetes in people already in danger of having the disease, new research shows.
In a paper published in the British Medical Journal, a team of scientists led by Jill Crandall of the Albert Einstein College of Medicine in New York, US, reports that in people at high risk of developing diabetes statin use heightened the chances of doing so by 30%.
To make their finding, Crandall and colleagues used data obtained during a long-running US study known as the Diabetes Prevention Program Outcomes Study (DPPOS).
The DPPOS was set up initially to discover whether a combination of weight loss, exercise and diet was better than a drug called metformin at preventing the onset of diabetes in people who showed no clinical symptoms of the disease but had blood glucose levels that indicated they were at risk of developing them.
The study tracked 3234 volunteers recruited through 27 treatment centres. The first tranche of results, published in 2002 in the New England Journal of Medicine, found that the exercise-diet regime was more effective than metformin. (Those taking the drug still recorded positive, albeit less pronounced, health outcomes.)
These included three meta-analyses. Typical was the 2010 study published in The Lancet and led by Naveed Sattar of the University of Glasgow, Scotland, that found “statin therapy is associated with a slightly increased risk of development of diabetes, but the risk is low both in absolute terms and when compared with the reduction in coronary events”.
These studies, however, had taken a wide range of statin users as their focus. Crandall and her colleagues opted instead to look specifically at people already identified as being at significant risk of developing diabetes.
At the start of the DPPOS, fewer than 4% of the participants were taking statins. After a decade, however, more than one-third were doing so.
The team noted that the likelihood of being prescribed statins rose sharply after a diagnosis of diabetes. However, they also observed a counter-trend: being prescribed statins was associated with an increased likelihood of subsequently being diagnosed with diabetes.
The risk – estimated at 30% — was constant regardless of whether high or low potency statins had been prescribed, nor was it affected by LDL (“bad” cholesterol) density.
The finding is to a degree unexpected. In addition to lowering cholesterol, statins have also been linked to a range of other beneficial outcomes, including reducing inflammation and improving circulation. These, note the researchers, should lead to a reduction in diabetes risk, but this is not confirmed by the results.
The scientists stress that their results are observational, and no causal relationship between statins and diabetes can be inferred from them. They also counsel that although a modest increase in diabetes risk has been identified, this must be weighed in the context of the potentially much larger decrease in heart attack and stroke risk associated with taking statins.
Commenting on the study, neurologist Craig Anderson of the University of New South Wales in Australia, notes the results had been drawn from a carefully monitored population over several years.
“The data appear robust and, while statins provide clear benefits in terms of cardiovascular prevention, these effects may be offset somewhat by an increase in the risk of diabetes over time and should be monitored for in patients,” he says.