Reducing weight by 10 per cent cuts the risk of developing the disease by up to 90 per cent in those most susceptible.

This can be safely achieved by following a strict calorie-controlled programme, researchers say.

The breakthrough findings will be presented to a gathering of top specialists at a European obesity summit in Sweden tomorrow.

They come from a two-year study set up in response to the recognition that Type 2 diabetes is the world’s fastest growing chronic disease.

Eight countries, Britain, Denmark, Finland, Holland, Bulgaria, Spain, New Zealand and Australia, collaborated in the largest controlled trial of its kind.

The Preview study was set up to find the best way to prevent Type 2 diabetes by diet and exercise.

Its 2,300 volunteers, all of whom showed the signs of pre-diabetes, weighed an average 15st 8lb before the study began in 2014.

They each consumed just 800 calories a day from soups and milkshakes for eight weeks.

Initial findings show they lost an average of 23lb or 10.8 per cent of their body weight.

Professor Jennie Brand Miller of the University of Sydney, who took part in the study, said: “In many cases their blood glucose is back to healthy levels and their pre-diabetes has disappeared.”

Millions of overweight Britons have prediabetes, in which blood glucose levels are elevated but are not yet high enough to be diagnosed as Type 2.

Between five and 10 per cent go on to develop the full-blown condition.

Adrian Brown, a specialist weight management dietitian at Imperial College, London, said: “We know losing weight is the key to preventing diabetes, along with permanent dietary change and more physical activity.

“The more weight lost initially, the greater the chance of people remaining clear of diabetes for longer, provided they can keep the weight off.

“With evidence from other studies, we can be confident the 10.8 per cent weight loss from the diet, if maintained, would be associated with a 90 per cent reduction in diabetes risk over three years.”

Dr Anthony Leeds, an obesity specialist at Central Middlesex Hospital, said: “The more weight lost and maintained, the greater the proportion of people who remain diabetes-free. “They need to lose and keep off about 10 per cent of their weight.”

An international coalition of diabetes campaigners said last week that surgery to reduce obesity should be a standard NHS treatment for Type 2 diabetes.

Simon O’Neill, of Diabetes UK, said: “We strongly support the call for obesity surgery to be fully recognised as an active treatment option alongside established forms.

“A wide body of evidence shows surgery is an effective treatment option.”

Britain now has more than four million Type 2 sufferers, with another 12 million at risk due to chronically unhealthy lifestyles.

The NHS already spends £10billion a year managing the condition, in which complications can include blindness, amputations, heart and kidney disease.

Experts fear a diabetes time bomb has the potential to bankrupt the NHS. Full results of the Preview study are expected to be available later this year.