We often hear about diabetes as one of the downsides of obesity. But there is still a lot of confusion about the disease, its causes and its treatment.

One of the odd things about diabetes is that it is, in some respects, more than one disease. Type 1 diabetes, or insulin dependent diabetes mellitus, is the sort that suddenly hits children and younger people when their body no longer produces insulin, produced in the pancreas to regulate blood sugar levels. This form used to be called juvenile diabetes.

If you are lucky, you learn to cope with daily injections of insulin for the rest of your life, and how long that is depends on a rigorously disciplined approach to control the diabetes. We tend to take insulin treatment for granted. But, in some parts of the world, it is a different story. If you are unlucky enough to be a child with diabetes in in sub-Saharan Africa, after being stricken with type 1 diabetes, the rest of your life can be as short as seven months. Type 1 diabetes can be a death sentence for many unfortunate young victims.

But type 2 diabetes is what we are really referring to when we talk about the consequences of overweight and obesity. It used to be called NIDDM — non-insulin dependent diabetes mellitus — and it accounts for more than 90 per cent of diabetes worldwide.

For the 1.6 billion people who are already overweight or obese globally — and who therefore provide the most eligible candidates for suffering from type 2 diabetes — the concept of education and prevention may have come a little late in the day. WHO research experts have estimated that overall diabetes cases will double to 366m by 2030, compared with 171m in 2000.

This is why taking serious steps to address overweight and obesity is given so much emphasis. Recent research from Sweden is already signposting a way forward. A new analysis confirms that the size of abdominal fat cells and a waist-to-height ratio clearly predicted women who were likely to develop type 2 diabetes. There is ample evidence that type 2 diabetes can be avoided.

The latest follow up to diabetes prevention programmes confirms how the remarkable effect of “intensive lifestyle intervention” (basically, changing diet and exercise habits) is more powerful that the commonly prescribed drug treatment with metformin. In the early stages, the lifestyle effect reduced the incidence of diabetes by 58 per cent, compared with 31 per cent for the drug. A decade later, researchers found that diabetes incidence was reduced by 34 per cent among the lifestyle group, but by only 18 per cent for the group receiving drug therapy.

This lends great strength to the theme set by the International Diabetes Federation for World Diabetes Day over the next five years.

It may be too late for some, but it suggests that we need not accept that a doubling of diabetes is inevitable. Education and prevention — if it results in intensive lifestyle changes — can be a lifesaver, too.