We know that the weight loss of Type 2 diabetes can be reversed.
But so far no-one thinks when you start to lose weight is essential.
Now, we know earlier that you lose weight, better. Experts say you should shed pounds as soon as you are diagnosed if you want to beat the disease.
Getting a strict 800-calorie diet within a few years after you have been diagnosed more likely to improve diabetes than to stay longer.
The reason is Type 2 diabetes without control over a three-year period can damage the insulin generating cells of the pancreas beyond repair.
A study from the University of Newcastle looked at data of 298 adults diagnosed with the condition about six years ago.
The participants, aged between 20 and 65, ate only 825 to 853 calories a day for between three and five months before moving on to a healthy diet.
Almost half (46%) of them were free of Type 2 a year later, compared to only 4% that did not go on the diet.
The study queried why weight loss treats some patients but not others.
The scientists looked at 40 who were in respect of 18 who had a condition.
They even found that when these patients had a similar weight loss, some had gone in to eliminate, but some still had diabetes.
The patients who had gone into displaying early and lasting improvements in their function of beta cell, cells in the pancreas that produced insulin.
After losing weight, the beta cells of those who were discharged began to work very well yet, but they were not those with Type 2 diabetes.
This is where the time of treatment is essential. On average, those who left with continuity had been living with him for a shorter period than those who were still infected with the disease.
"Our findings suggest that the longer person has lived with Type 2 diabetes, the least likely the role of their beta cells is likely to improve," said lead author Professor Roy Taylor.
"The clinical message is clear: the new method of weight loss should be advised to all those with Type 2 diabetes, especially at the time of diagnosis."
Dr Elizabeth Robertson, research director at Diabetes UK, said we now know why some people can give their diabetes to be respected, but others can not.
This is important news for one in 15 people in the UK who have developed the condition.