Intensive treatment to control blood pressure and glucose levels in sufferers can dramatically reduce their risk of complications, but it has not been routinely offered because there was no firm evidence until now that it made any difference. Instead, many patients have been left to control the disease by restricting their diet.
Results from a clinical study of diabetes that was started 20 years ago were presented yesterday at a conference in Barcelona and are published in a series of five papers in the British Medical Journal and The Lancet today.
They show that if drug treatment is started as soon as blood pressure or blood glucose rise above an agreed target, the risk of death, strokes, kidney damage and loss of vision are cut by a third.
The findings relate to Type 2 (non-insulin dependent) diabetes which comes on in middle age and is normally controlled by diet. It accounts for 90 per cent of all cases of diabetes and is distinct from Type 1 which affects the young and requires daily insulin injections.
Type 2 diabetes is rising rapidly and is expected to affect 3 million people by 2010. It is commonest in the overweight.
Professor Robert Turner of Oxford University, who led the study of more than 5,000 patients, said: "This study shows for the first time that a substantial improvement in the health of people with Type 2 diabetes can be obtained."
Professor Turner said the drugs involved were cheap and the extra costs of intensive treatment would be largely offset by savings from reduced hospital admissions.
Poor detection of diabetes, which is marked by increased thirst, weight loss and extreme tiredness, means that many sufferers live with the condition for years before being diagnosed.
The study has taken 20 years to complete because the complications come on over decades and it required a lengthy study to show that treatment could prevent them.