The team from Glasgow University calculated that use of statins increased the risk of type-2 diabetes by around 12 per cent after four years. Those taking the drugs also gained an average of around 240g in weight.
But after identifying that statins had this effect due to the same mechanism which led to them reducing cholesterol, the researchers said the drugs still did more good than harm and patients should continue to take them as directed.
Working with colleagues at University College London, the experts said these negative effects could be reduced by patients making lifestyle changes such as exercising and eating a healthy diet.
The findings, published in the Lancet, come after a long-running debate over whether more patients should be prescribed statins to reduce their risk of heart attacks and stroke due to concern about the potential side-effects.
While the drugs have previously been linked to type-2 diabetes, the researchers examined results from 130,000 participants in clinical trials to calculate the 12 per cent increased diabetes risk and 240g weight gain reported in their study.
They then went on to examine why statins may have this effect on diabetes risk.
Statins reduce low-density lipoprotein cholesterol by inhibiting the action of a particular liver enzyme. The team also concluded that there was no evidence that a person’s genetic make-up would affect their response to statin treatment.
The researchers stressed that statins should continue to be prescribed according to current guidelines, and that patients should be given advice on their lifestyle to help combat any increased risk of diabetes and weight gain they face.
Researcher Professor Naveed Sattar, from Glasgow University’s Institute of Cardiovascular and Medical Sciences, said: “Previous analyses have indicated the cardiovascular benefits of statin treatment greatly outweigh the risk of new-onset type-2 diabetes.
“Nevertheless, many patients eligible for statin treatment would also benefit from lifestyle changes including increased physical activity, eating more healthily and stopping smoking.
“The modest increases in weight and diabetes risk seen in this study could easily be mitigated by adopting healthier diets and lifestyles.”
Prof Jeremy Pearson, of the British Heart Foundation, said: “Statins offer substantial protection from coronary heart disease. This study looked at why people taking them have a small increased risk of diabetes.
“This study should reassure people that the benefits of taking statins far outweigh the small effect on diabetes risk.
“But the results also reinforce that, alongside prescribed medication, taking steps to maintain a healthy weight is essential to stay heart healthy.”