Statin treatment does raise the likelihood that patients with risk factors will develop diabetes, but this is more than outweighed by the cardiovascular benefits of treatment, say researchers.
The analysis of 17,603 patients taking statins for primary prevention showed those with at least one risk factor for diabetes were 28% more likely to develop diabetes when taking the drugs, compared with patients in the control group.
But those taking statins were also 39% less likely to develop cardiovascular illness and 17% less likely to die than controls over the five-year trial period.
Earlier this year the US Food and Drug Administration added a warning about the risks of diabetes to statins after results from the JUPITER primary prevention trial, with European regulators also raising concerns.
Now further analyses of the trial data published in The Lancet have shown that the association is dependent on whether the patient was already at risk for diabetes, but that it still overshadowed by the reduction in cardiovascular risk.
For those who had no existing risk factors for diabetes – including metabolic syndrome, impaired fasting glucose, body-mass index of 30 kg/m2 or higher, or HbA1c greater than 6% – there was no discernable added risk when taking statins compared with controls.
These patients had a 52% reduction in cardiovascular illness when taking the cholesterol-busting drugs, compared with controls.
The team from Harvard Medical School calculated that for those with diabetes risk factors, 134 vascular events or deaths were avoided for every 54 new cases of diabetes diagnosed.
This compares with 86 vascular events or deaths avoided with no new cases of diabetes diagnosed in those with no existing risk factors.
Study leader Professor Paul Ridker, professor of medicine at Brigham and Women's Hospital in Boston, said the results showed the absolute benefits of statins were greater than the risk of developing diabetes in all patients.
He said: ‘We believe most physicians and patients would regard heart attack, stroke and death to be more severe outcomes than the onset of diabetes, so we hope these results ease concern about the risks associated with statin therapy when these drugs are appropriately prescribed in conjunction with improved diet, exercise and smoking cessation to reduce patients' risk of cardiovascular disease.'
Dr Terry McCormack, a GP in Whitby, North Yorkshire, said the study proved the value of statin treatment.
He said: ‘This paper shows that it is not crossing a blood test line that matters as much as preventing cardiovascular events. Personally, I would be more interested in controlling my cholesterol than avoiding a tick-box measure of diabetes diagnosis.'