Long term use of statins is associated with a 30% heightened risk of developing type 2 diabetes in susceptible individuals, suggests a large study from the US.
The trend held true irrespective of other risk factors for diabetes or clinical criteria for statin treatment, according to the findings published in the journal BMJ Open Diabetes Research and Care.
The researchers noted that a small increase in diabetes risk from statins had been observed before, but mostly where the absolute risk of developing the condition was relatively low in participants.
- Different levels of diabetes risk linked to different statins
- Taking statins linked to ‘higher diabetes risk than previously thought’
In contrast, their study involved 3,234 participants from the US Diabetes Prevention Program Outcomes Study, who were overweight and obese with a high risk of type 2 diabetes.
It followed up a trial that looked at whether modest weight loss through lifestyle changes or treatment with metformin could reduce or delay development of diabetes in high risk patients.
The trial participants were given standard advice on healthy eating and exercise, and were randomly assigned to either an intensive lifestyle programme, treatment with metformin, or a placebo.
After the trial, those who took part in the 10-year follow-up had their cholesterol and blood pressure measured annually. Blood glucose was measured twice a year, at which point new statin treatment was also recorded.
“We observed significantly higher rates of diabetes with statin therapy in all three treatment groups”
At the start of follow-up study fewer than 4% of participants were taking statins, but use of the drugs gradually increased until after 10 years around a third of the participants were taking them.
The most commonly prescribed statins were simvastatin and atorvastatin, said the researchers, with 40% of patients taking the former and 37% the latter.
The likelihood of a statin prescription rose substantially after a diagnosis of diabetes. But statin use was itself associated with a heightened risk of being diagnosed with diabetes, irrespective of which treatment group the participants had been in during the trial, said the researchers.
When all groups were combined, being prescribed statins was associated with a 36% heightened risk of going on to be diagnosed with type 2 diabetes, compared to other patients.
The researchers noted that the risk fell slightly to 30% after taking account of the clinical criteria used to determine the need for statin treatment.
They said that although those who were prescribed statins had slightly higher levels of blood glucose to start with, it did not explain their higher rates of diabetes.
Meanwhile, they found no link between the potency of the statin used and diabetes risk, nor between the reduction in low density lipoprotein.
The researchers highlighted some previous experimental research suggesting that statins may impair the production of insulin, the hormone needed to lower the body’s levels of blood glucose.
They also noted that a potentially modest increase in diabetes risk needed to be weighed carefully against the significant reductions in the risk of a heart attack or stroke afforded by statin treatment.
“In this population at high risk for diabetes, we observed significantly higher rates of diabetes with statin therapy in all three treatment groups,” said the study authors.
“A potential modest increase in diabetes risk clearly needs to be balanced against the consistent and highly significant reductions in myocardial infarction, stroke and cardiovascular death associated with statin treatment,” they said.
“Nonetheless, glucose status should be monitored and healthy lifestyle behaviours reinforced in high-risk patients who are prescribed statins for cardiovascular prophylaxis,” they added.
“It is important that people who have been prescribed statins continue to take their medication”
Commenting on the findings, Pav Kalsi, senior clinical advisor at Diabetes UK, said: “Statins can significantly reduce the risk of heart attacks and strokes, so it is important that people who have been prescribed statins continue to take their medication.
“There are a number of different factors that can increase a person’s risk of developing type 2 diabetes,” she said. “To reduce this risk, we recommend that people follow a balanced diet, do regular physical activity, maintain a healthy weight and have regular check-ups.”
Last year, UK researchers said the benefits of statin therapy had been repeatedly underestimated and the harms exaggerated, due to misinterpretation of the evidence.
In a major review of the available evidence on the safety and efficacy of statin therapy, published in The Lancet, they said there had previously been a failure to acknowledge properly both the wealth of evidence from randomised trials and the limitations of other types of studies.
As reported by Nursing Times, several other previous reviews have also concluded that the benefits of statin therapy far outweigh the risks of side effects, including that of developing diabetes.