BBC health reporter
Soaring childhood obesity rates will increase diabetes rates affecting economic development across the globe, international agencies are warning.
Being overweight has health risks, scientists say
The caution from the WHO and the International Diabetes Federation comes on World Diabetes Day.
They say with an estimated 10% of school-aged children overweight or obese the situation is getting worse.
More than 22 million children under five years old are obese or overweight, not only from affluent countries.
Over 17 million of them are in the developing world.
Each one of these children is at a much higher risk of developing type 2 diabetes.
This used to be known as adult onset diabetes as it would be diagnosed late in life, but because of poor diet and little physical activity the disease is now being seen more often in teenagers.
There are also other risks associated with being overweight - heart disease, stroke, cancer and there's some data to suggest that conditions like Alzheimer's might also be linked.
But the obesity epidemic can be reversed.
Just small changes can make real difference - banning fizzy drinks in schools, increasing sport classes and teaching basic nutrition from an early age can prevent weight gain, therefore reducing the chances of diabetes developing.