Research published in the British Medical Journal found that between 16 and 21% of patients offered the chance to check their blood sugar levels at home did not even bother to take their prescription to a chemist.

And few patients carried out the recommended number of tests each day.

But doctors noticed that those who made a conscientious effort to frequently check their levels enjoyed better health.

The home testing kits use reactive strips which, when in contact with a drop of blood, show when sugar levels are too high.

Most diabetics require the correct levels of insulin injection to keep their blood sugar levels stable.

Unstable blood sugar levels can lead to complications such as blindness, strokes and heart disease.

£400 a year per patient

In 1995, £42.6m was spent on self-monitoring of blood sugar levels in the UK, although some experts cast doubt on its effectiveness.

Some diabetics are failing to test their own sugar levels

The researchers found that, on average, it cost just over £400 a year per patient to self-monitor, and the cost was much higher to the NHS if the patient developed complications.

The study, carried out at the Ninewells Hospital and Medical School in Dundee, found that blood haemoglobin levels - a measure of good health in diabetics - were higher in those who were taking part in some form of self-monitoring.

But teenagers and young adults were worse at checking their levels, as were those from areas of higher social deprivation.

Dr William Kenny, a diabetes specialist from Middlesbrough General Hospital, said that his experience with self-monitoring was favourable.

He said: "It is important to prevent complications, and 85% of our patients do their own testing.