Doctors are famously gloomy about Type 2 diabetes: those who have had the misfortune to be diagnosed with it will have heard words such as ‘incurable’ and ‘progressive condition’, possibly accompanied by a shake of the head – the GP’s equivalent of a tutting builder. However, recent research may give the UK’s 2.6 million sufferers cause for optimism as scientists at Newcastle University have shown that you can actually reverse diabetes if you lose enough weight.

They chose volunteers who had Type 2 diabetes and a height/weight ratio in the Body Mass Index (BMI) obese category of over 30. The volunteers stopped taking their medication and went on a diet of just 600 calories a day - the recommended daily amount for a four-month-old baby. They were allowed meal replacement diet drinks plus green vegetables for eight weeks.

Eleven of the 14 volunteers lasted the course, losing an average of 2st 5lbs (15kg), with BMI down to 29 – overweight rather than obese. After a week their blood sugar levels had returned to normal, and by the end of eight weeks their diabetes had disappeared. Study leader Professor Roy Taylor believes that – technically at least – this counts as a cure, although he doesn’t like the word because to succeed you need bucketfuls of willpower.

‘I don’t want to raise people’s hopes because this cure involves great determination,’ he says. ‘Probably only a few per cent have the motivation and determination to achieve this weight loss – and keep it off.

‘But what we have shown should make a profound difference to what people are told at diagnosis. It is not a life sentence; it is potentially capable of being reversed.’

Doctors notice a similar effect after gastric surgery. After a gastric bypass, 85% of patients find their diabetes has disappeared within a couple of days. Scientists don’t know if it’s the sudden weight loss that causes it or hormonal changes in the gut. With a gastric band the effect is more gradual, but within two years 73% are off their medication, according to an Australian study.

So what’s happening in the body? When we lose weight, it’s the fat cells in the pancreas and liver that disappear first – and the pancreas is where insulin is made. It’s the body’s inability to make enough insulin and process it correctly that causes Type 2 diabetes. In the Newcastle study, an MRI scan of each volunteer showed that as pancreatic fat levels fell, insulin production restarted and the weight loss also seemed to help with insulin resistance (where the body becomes less sensitive to insulin).

Prof Taylor doesn’t believe the speed of the weight loss is important: one woman (not part of his study) took nine months to lose two stone by dieting and her diabetes disappeared.

He is now looking at whether the regime might work with those who have had diabetes for longer (the volunteers had been diagnosed an average of four years previously) or who take insulin. ‘We know that even if you are on insulin and lose weight the diabetes will improve. I can’t be definitive, but there’s very good reason to believe most people can reverse their diabetes with sufficient weight loss.’

His volunteers were followed up three months after they had returned to normal eating. Most had regained a bit of weight – the average was 6.6lb (3kg) – but seven out of 11 remained diabetes-free. The others were just into the diabetes category.

So, how much weight can you put back on and remain clear? ‘I am sure you can’t put it all back, but each person will have started from a different point,’ says Prof Taylor. ‘For instance, although they have lost 2st 5lb [15kg], it may be that they needed to lose 3st 2lb [20kg] to take them out of the diabetes zone. Others may have done enough with 15kg. Individuals will have different thresholds.

‘Some may only need to get to a BMI of 30 to 35; but you see people with BMIs of 26 to 27 with diabetes, so they would presumably need to come down to the lower end of the healthy range.

Dr Iain Frame, director of research for Diabetes UK, warns against extreme dieting without medical supervision. ‘You’re actually talking about starving yourself for eight weeks. These people were surrounded by medical and nutritional help. People are looking for quick fixes but healthier eating and more exercise is what works.’

He is concerned that such fast, intense weight loss might lead some people down a path of yo-yo dieting – bad news for diabetics. Studies have shown that 83% of those who lose a lot of weight within six months had put on more than they lost two years later.

‘I think there’s an argument to be made for someone to try this when they are overweight and struggling – if they can lose a stone quickly and then be inspired to take up healthy eating and exercise (to kick-start their weight loss) then I wouldn’t have a problem with that, as long as they are supervised very closely,’ says Dr Frame.

The question of how best to lose the weight is not something all agree on. The traditional diet recommended for Type 2 diabetics has been low fat and high carbohydrate. But there is a growing feeling that it might be better to cut the carbohydrate element.

The American Diabetes Association is examining its nutritional guidelines and will reissue them next spring. Meanwhile, it doesn’t rule out low-carb diets: ‘Either low- carbohydrate or low-fat, calorie-restricted diets may be effective in the short term – up to one year.’ However, doctors should monitor the lipid profiles and renal function of those on low-carb diets, and points out that it’s increased exercise and ‘behaviour modification’ that are most helpful in maintaining weight loss.

Diabetes UK is in the process of updating its guidelines, but it’s proving controversial and publication has been delayed several times.

Meanwhile, research has backed lower-carb and low Glycaemic Index diets, including a review of studies by the Cochrane Collaboration, a not- for-profit organisation that makes up-to-date, accurate information about the effects of health care available worldwide.

Doctors urge caution on really low-carb diets. ‘Low-carb diets work for a short time in some people, but carbs are necessary for survival. If you cut them out completely, in the end your kidneys collapse and your muscles waste away,’ says Dr Frame.

Prof Taylor believes how you lose the weight is not as important as the fact that you lose it: ‘It’s calorie restriction that counts, not which food groups they come from.’

He’d like more appreciation among professionals that diabetes can be reversed this way.

‘Among the hundreds of emails I got from patients, by far the most common complaint was that their GP told them what we had done was impossible because diabetes never goes away. That is not true. We’ve proved it.’

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