Beta-blockers 'increase diabetes risk by 50 per cent'


Last updated at 22:00 06 September 2006

Patients taking beta-blockers for their blood pressure have a 50 per cent higher risk of developing diabetes compared to being on newer drugs, researchers have revealed.

For the first time, a new study reveals the risk of using the older drugs which are no longer recommended for treating high blood pressure.

Patients taking beta-blockers and diuretics - standard medication for over 30 years - are at far greater risk of becoming diabetic.

Not only are they less effective than newer medication, but they actually hasten and, in some cases, induce the disease in blood pressure patients - who are already at high risk.

This means at least 8,000 Britons taking the older drugs are getting diabetes unnecessarily each year as a result.

Until earlier this year, around two million patients have been on beta blocker based treatments at any one time.

But new guidance to doctors says newer ace inhibitors and calcium channel blockers should be the first choice treatment for the millions of Britons treated for high blood pressure.

The change came after research found the older drugs were only half as effective at stopping strokes and heart attacks.

Beta blockers such as atenolol should no longer be prescribed for the problem, said the guidelines from the National Institute for Clinical Excellence.

But now a new clinical trial released yesterday show they also bring a 50 per cent higher risk of developing diabetes.

Although many patients currently taking them are being switched by their GPs to newer drugs when they go for a scheduled check-up, they remain in wide use.

Beta blockers are still considered the best treatment for other conditions such as angina, and doctors have warned patients not to stop taking them without medical advice as sudden withdrawal may trigger a heart attack.

Professor Neil Poulter, Co-Director of the International Centre for Circulatory Health, Imperial College London, who led the trial, said: 'Chances of a patient with raised blood pressure developing diabetes can be cut by the newer treatment irrespective of the patients initial level of risk.

'Many new cases of diabetes could be prevented as a result, if GPs avoid prescribing the older treatments to hypertensive patients unless they specifically require them.'

Benefits outweigh risk in some cases

Experts stress that, for remaining beta blocker patients, the benefits in lowering blood pressure still massively outweigh the diabetes risk, so they should not suddenly stop taking them.

But they also called for all patients to be switched to the new drugs as soon as possible.

The trial results were released at the World Congress of Cardiology in Barcelona.

The study looked at 14,000 patients in the UK, Ireland and Scandinavia, half of whom were taking the old style combination of the beta blocker Atenolol and a diuretic.

The remainder were prescribed a calcium channel blocker called amlodipine and the ace-inhibitor perindopril, and in this group 34 per cent fewer patients developed diabetes over three years.

The study suggests the ace-inhibitor provides protection against the condition while the other drug is neutral.

But the beta blocker and diuretic combination actually has an adverse effect in encouraging diabetes.

Having diabetes and high blood pressure together greatly increases the risk of heart attacks, strokes and kidney disease.

Professor Poulter, Professor of Preventive Cardiovascular Medicine, said: 'The result emphatically adds to the evidence that beta blockers and diuretics can exacerbate that risk.

They have been great drugs for a long time but there is a down side and we have to stop pretending that it's ok to give people diabetes. These cases are absolutely unnecessary.

'The newer drugs are better at stroke prevention, more cost effective and don't give you diabetes.'

He estimates around 8,000 cases of diabetes each year in the UK can be blamed on the old style drugs, out of the 100,000 new cases diagnosed each year.

But, he added, older drugs were not responsible for fuelling a surge in cases in recent years - nearly three million people have diabetes, although one million are unaware of it.

Obesity and lack of physical activity have been much bigger risk factors.

Professor Poulter stressed that patients on beta blockers must not suddenly stop taking them. 'They are still the right drugs for some people and your doctor can advise you'.

Prof Peter Weissberg, medical director of the British Heart Foundation charity, said: 'The evidence shows there is a better outlook for the newer drugs in delaying or preventing diabetes in patients with high blood pressure and this has led to the new guidelines.

'The message is getting through to GPs, but there are other important reasons for being on a beta blocker, such as angina, arrhythmia and heart failure, where they are life-saving.

'Patients taking a beta blocker should not stop taking them without seeing a doctor. If you stop it suddenly, then it may cause a major event, possibly a heart attack.'

Amanda Eden, care adviser at the Diabetes UK charity, said: 'These findings are interesting, as we know that high blood pressure is both a risk factor and complication of diabetes.

'Nevertheless, when it comes to prevention, other factors, such as leading an active lifestyle and following a healthy diet are also essential.'


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