More than 200 under 14s in the UK – some as young as five – were treated for type 2 diabetes last year – a disease normally only associated with the over 50s.
Medics say the situation will only get worse unless children eat more healthily.
And diabetes is a particular concern for children as it affects them more severely than adults.
Hospitals have already seen youngsters admitted with early kidney disease.
The key, doctors agree, is diet – but they warn the country is sitting on a treatment time-bomb which could end up bankrupting the NHS.
Dr Justin Warner, who leads the National Diabetes Audit for England and Wales, run by the Royal College of Paediatrics and Child Health, said: “Ten years ago type 2 diabetes in children’s centres was almost unheard of. Now we are seeing hundreds of cases.
“The food industry needs to be regulated by the Government and we need more education in schools.
“Type 2 diabetes in children often presents in a more severe form with complications such as early signs of kidney disease and high blood pressure. This ramifications are huge putting a massive burden on the individual, the family and NHS.”
Professor Philip James, founder of the International Obesity Task Force said: “We are jacking up the next generation of trouble and the NHS cannot cope with the current levels of diabetes and obesity and will be bankrupted by this in the future unless action is taken.”
Dentists are also concerned about youngsters’ diets. More than 45,000 under 14s were hospitalised last year for rotten teeth to be extracted.
Dentist Tony Kilcoyle, a campaigner for better child health, said growing admissions for severe tooth decay were an early warning sign of a child diabetes epidemic.
Tooth extraction is now the number one reason for children being admitted to hospital.
Last year 45,532 were operated on, up nearly twenty per cent on a decade ago.
Dr Kilcoyle said: “It is already tragic now, but over the next ten years the problem of childhood type two diabetes will be epidemic unless urgent action is taken.”
“Children are becoming addicted to sugary foods and fizzy drinks. This rots the teeth first and stores up diabetes in the future.
“Levels of tooth decay are going up. Levels of childhood diabetes are going up. Bad diet is the link.”
Current figures show 533 under-19s were diagnosed with type 2 diabetes, including 11 aged five to nine, 204 aged 10-14 and 318 aged 15-19.
About a fifth of five year olds and one in three aged 10 is overweight or obese. Based on current trends, half of all children will be obese or overweight by 2020.
The Government launched an anti-obesity strategy last August to tackle the problem.
Its measures, centred on a sugar tax, rely on voluntary action by the food and drink industry and are shorn of any restrictions on junk food adverts.
But Prof. James said: “We cannot rely on a profit-hungry industry to put the health of the nation first.”