Leading diabetes drug 'raises risk of heart attack'

The world's top-selling oral diabetes drug increases the risk of a heart attack by almost half, according to new research.

The finding is a serious blow to sufferers from Type 2 diabetes, of which there are 1.8 million in the UK. Avandia, taken by an estimated seven million people around the world and 150,000 in Britain, was hailed as a major advance against the disease when it was launched in 1999.

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The drug lowers blood sugar levels which can cause complications including kidney and eye damage in diabetics, who lack the hormone insulin which converts blood sugar to energy.

But a review of 42 studies involving 15,560 patients who took the drug and 12,283 patients who were given other medications or a placebo found those on Avandia had a 43 per cent increased chance of having a heart attack.

The results were released early yesterday by the New England Journal of Medicine (NEJM) ahead of publication next month because of their importance.

Steven Nissen, the chairman of cardiology at the Cleveland Clinic in Ohio, who led the review, said: "The results of this analysis raise serious concerns about the cardiovascular safety of rosiglitazone (the chemical name for Avandia). Unfortunately, rosiglitazone appears to increase, rather than decrease, the most serious complication of diabetes, heart disease."

GlaxoSmithKline, the UK-based manufacturers of Avandia, last night issued a rebuttal of the findings in the NEJM. "GSK strongly disagrees with the conclusions reached in the NEJM article, which are based on incomplete evidence and a methodology that the author admits has significant limitations," the company said in a statement.

Matt Hunt, science information manager at Diabetes UK, said people should not be panicked by the findings, while the British Heart Foundation said patients should consult their doctors before stopping medication.

Mr Hunt said: "Diabetes UK does not believe that these findings are cause for alarm. Glitazones are not presently recommended for people who have had, or who are at high risk of having, heart failure."

Glaxo's shares fell by 5 per cent on the London Stock Exchange last night, the biggest fall in four years. Avandia generated sales of $3 bn (£1.5m) worldwide last year.

In an accompanying editorial in the NEJM, Bruce Psaty, of the University of Washington's cardiovascular health research unit, and Curt Furberg, of Wake Forest University's division of public health sciences, said in light of the potential heart risks the rationale for prescribing Avandia "at this time is unclear".

The new findings "represent a valid estimate of the risk of cardiovascular events, rosiglitazone represents a major failure of the drug-use and drug-approval process in the US," they added.

The researchers warned that their findings were not definitive. There were 158 heart attacks and 61 deaths from cardiovascular causes among the patients, and attributing just a few of those events to other causes could change the findings.

"Nonetheless, our findings are worrisome because of the high incidence of cardiovascular events in patients with diabetes," the researchers said. "Because exposure of such patients to rosiglitazone is widespread, the public health impact of an increase in cardiovascular risk could be substantial if our data are borne out by further analysis and the results of larger controlled trials."

While heart disease is the leading cause of death worldwide, diabetics are particularly susceptible because the condition can damage the heart muscle. Avandia helps sensitise the body to insulin and was considered a breakthrough medication for blood-sugar control.