A drug taken by hundreds of thousands of diabetics can increase their risk of suffering a fatal heart attack or heart failure, researchers say.

Avandia, taken daily by 240,000 Britons to treat type 2 diabetes, can increase the risk of heart failure by as much as 60 per cent among older patients, and increase risk of death by 29 per cent, a large study from Canada suggests.

Heart failure, in which the damaged organ gradually loses the ability to pump blood around the body, typically kills 40 per cent of sufferers within a year of its onset. Avandia is thought to exacerbate the problem by aiding fluid retention, meaning that the heart needs to work harder to pump a greater quantity of blood around the body.

In July, the US Food and Drug Administration (FDA), advised that the drug should be pulled from chemists’ shelves, after a smaller study associated it with an increased risk of heart attack. But British and European medicine watchdogs insisted yesterday that a recent review of Avandia and related drugs had concluded that their benefits outweighed their risks.

Avandia, also known as rosiglitazone, comes from a family of medicines known as thiazolidinediones (TZDs) which have previously been linked to heart problems as well as thinning bones and osteoporosis.

The drugs are oral hypoglycaemic agents, designed to help control blood sugar levels in patients with type 2 diabetes, the form of the disease which is linked to obesity and tends to occur from middle age onwards. Type 1 diabetes involves a lack of insulin, and requires supplements of the hormone to control blood sugar levels, whereas in type 2 patients TZDs can act on muscle, fat and the liver to increase use of glucose and diminish its production.

Lorraine Lipscombe, of the Institute for Clinical Evaluative Sciences in Toronto, and colleagues, evaluated the risks of heart failure, heart attack and death associated with the use of TZDs, compared with other oral hypoglyc-emic agents among patients aged 66 years or older with diabetes.

The research, publised in the Journal of the American Medical Association today, analysed data from 159,026 people with diabetes in Ontario who were monitored for an average of 3.8 years, until March 2006. During this time, 7.9 per cent of patients had a hospital visit for congestive heart failure, while a similar number (12,500) visited hospital for a heart attack and 19 per cent (30,265 patients) died. Compared with the other medications, this meant that users of TZDs had a 60 per cent increased risk of congestive heart failure, a 40 per cent increased risk of heart attack and a 29 per cent increased risk of death, the study found.

“While improved glycaemic control has been linked to better clinical outcomes in diabetes, and TZDs have been suggested as having potential car-diovascular benefits, recent concerns have arisen regarding adverse cardiac effects of these drugs,” the authors wrote. Although the researchers studied a range of drugs, the significantly increased risks appeared only with Avandia, they said.

Previously, when the FDA investigated the drug, a panel voted against removing rosiglitazone from the market because of insufficient data. But today’s study provides more compelling evidence of the health risks, the researchers said.

The European Medicines Agency, which controls licensing of Avandia in Britain, recommended in October that the safety of the drugs should be researched further but advised patients with any concerns to speak to their doctor or pharmacist.

Avandia’s manufacturer, the pharmaceutical giant GlaxoSmithKline, acknowledges that there is a risk of heart failure. But it claims that thenew study has “significant limitations and generates misleading conclusions regarding acute myocardial infarction [heart attack], death and heart failure”.

But Andrew Hattersley, a diabetes consultant at the Royal Devon and Ex-eter Hospital, yesterday advised patients who were taking Avandia to try alternative drugs. “In the South West region we have some of the lowest prescibing of rosiglitazone and are increasingly pleased that’s the case,” he said.

Professor Hattersley urged anyone currently using Avandia to consult their GP if they started developing symptoms of heart failure. These include breathlessness, tiredness and fluid retention, leading to swollen legs.

Tracy Kelly, of the charity Diabetes UK, said the drugs are not recommended for people who have had, or are at risk of, heart failure. “Both the MHRA [the UK’s Medicines and Healthcare products Regulatory Agency] and the European Medicines Agency say that people should not stop taking glitazones and if concerned they should consult their doctor.”

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