Two drugs commonly prescribed to treat diabetes double the risk of heart failure, according to new research by the University of East Anglia (UEA).

Rosiglitazone (Avandia) and Pioglitazone (Actos) are recommended by the National Institute of Clinical Excellence (NICE) for the treatment of Type II Diabetes. Prescriptions for the drugs, known as thiazolidinediones, have doubled over the last three years and they were taken by more than 1.5 million people in England last year.

The new research was undertaken by Dr Yoon Loke, a clinical pharmacologist at UEA’s School of Medicine, Health Policy and Practice, working with colleagues at Wake Forest University in the US. The results are published in the August edition of the journal Diabetes Care.

Safety concerns emerged earlier this year when a link was drawn between Rosiglitazone and heart attacks. The new research confirms that treatment with thiazolidinediones doubles the risk of heart failure and hypothesises that fluid retention caused by the drugs provide the trigger.

The findings are based on a meta-analysis of more than 78,000 patients, which estimates that one in every 50 patients taking the drugs over a 26-month period will require hospital admission due to heart failure.

“This means that the diabetes drugs could have caused thousands of additional cases of heart failure, creating a substantial burden on hard-pressed NHS services,” said Dr Loke.

“I think NICE should re-evaluate their decision to recommend these diabetes drugs.”

The researchers also looked in detail at more than 200 cases of patients with heart failure related to the diabetes drugs and found that the problem developed even in patients taking low doses of the drugs.

While heart failure is often thought to be a problem affecting older patients, the researchers also found that one quarter of cases occurred in people younger than 60.

The manufacturers’ information leaflets say that rosiglitazone and pioglitazone should not be used in patients known to have heart failure, but this research indicates that the drugs can provoke the problem even in those without a history of heart disease.

“Most patients in the studies did not have heart failure prior to starting on treatment with these drugs,” said Dr Loke. “There doesn’t seem to be a group of patients who are safe from these side effects.”

Dr Loke’s co-researchers were Dr Sonal Singh and Dr Curt D Furberg, both of Wake Forest University School of Medicine in the US.

“These drugs are taken by more than seven million diabetic patients in the US alone, suggesting that several thousand could be harmed,” said Dr Singh.