Type II diabetes now affects 7,000 under-25's in England and Wales

The figure is around about 10 times the number previously reported.

The government has been warned that it must take action, and the charity is calling for a ban on junk food advertising and restrictions on supermarket promotions of unhealthy foods to help address the surge in cases of the disease, which is largely preventable.

The news comes after the Local Government Association said earlier this year that 22,000 children are now classed as severely obese when they leave primary school. The charity also called for better specialist support for young people with the condition to help manage their illness and reduce their risk of serious complications.

Professor Russell Viner, president of the Royal College of Pediatrics and Child Health, urged the government to act out on proposals set out in Britain's childhood obesity plan saying: "For many children, the development of type II diabetes can be prevented with lifestyle changes but this isn’t easy - they need support".

Type II diabetes is much more aggressive in young people and complications of the disease such as blindness, amputations, heart disease and kidney failure can appear earlier. Diabetes UK also warned that thousands more children and young people could be diagnosed with the condition over the coming years.

A spokesman for the Department of Health and Social Care said it was committed to halving child obesity by 2030: "We will be launching consultations to restrict promotions in shops for sugary and fatty foods, as well as a 9pm watershed ban on advertising.

"The upcoming NHS long-term plan will have prevention at its core and build on our existing work to keep people healthy and well."