Statins prescribed to guard against heart attacks and strokes could increase the risk of diabetes by almost 50 per cent, a major trial suggests.
A six-year study from Finland on almost 9,000 men found that those prescribed the cholesterol-lowering drugs were far more likely to suffer from poor blood sugar control, and signs of diabetes.
Researchers found that after results were adjusted for age, body mass index, family history of diabetes, and smoking, alcohol and exercise habits, those on statins were 46 per cent more likely to develop diabetes.
However, some experts criticised the research, as it was not a randomised controlled trial.
Those being prescribed statins were already likely to have a higher risk of diabetes, they said, given that both conditions are linked to lifestyle.
The study led by Professor Markku Laakso, Institute of Clinical Medicine, University of Eastern Finland and Kuopio University Hospital, Finland, tracked 8,749 men aged between 45 and 73 for six years.
None had been diagnosed as diabetic at the start of the trial, and just over 2,100 of the participants were on statins.
By the end of the trial, 625 men were diagnosed with diabetes, the research published in Diabetologia, the journal of the European Association for the Study of Diabetes, found.
The risk of diabetes rose in line with the dose of the statins prescribed, the study found.
Researchers said the drugs appeared to alter insulin sensitivity, and reduce secretion of the hormone, triggering diabetes.
Previous studies have suggested a small increased risk of diabetes from statins.
Researchers said the new findings suggested such risks may have been previously underestimated, and said the size of the study, and way it was carried out meant its conclusions were likely to be reliable.
Last July, health watchdogs recommended that statins should be offered to around 17 million people – anyone estimated to have a 10 per cent chance of developing heart disease within a decade.
Experts said up to 50,000 lives a year could be saved if the guidelines are followed.
The controversial guidance triggered heated arguments about the benefits and risks of the drugs, and criticism that insufficent trial data has been published about their side-effects.
Dr Aseem Malhotra, Honorary Consultant Cardiologist, Frimley Park Hospital, who has criticised the guidance, said: “This study confirms that statins directly increase the risk of developing diabetes.”
He said GPs should ensure patients were properly informed about the risks and benefits from the drugs before they decided whether to take them.
But some scientists criticised the new research, and said the apparent increase in the risk of diabetes in those prescribed statins may not have been caused by the drugs.
Prof Stephen Evans, Professor of Pharmacoepidemiology at the London School of Hygiene & Tropical Medicine said: “The users of statins were generally at higher risk of heart disease and differed in a number of ways, probably including several ways that were not measured,” pointing out that the study did not track the diets of those involved.
Prof Keith Frayn, Emeritus Professor of Human Metabolism at the University of Oxford, pointed out that the 46 per cent increase measured the relative rise in risk.
Overall, 11 per cent of those taking a statin developed diabetes, compared with 6 per cent of those not taking the drug, with differences reduced further when confounding factors were taken into account, he said.
Professor Peter Weissberg, medical director at the British Heart Foundation, said: “This study showed that it was patients taking a high dose statin who were most at risk of developing type 2 diabetes and, importantly, many of the patients who developed diabetes already had risk factors for diabetes at the start of the study. This suggests that statins may act by unmasking a pre-existing tendency to diabetes.”
“It is important that people taking statins because of existing cardiovascular disease should continue to take them as the benefits will outweigh the risks.”