Diabetes UK reported that 6,836 children and young adults have Type 2 diabetes in England and Wales, according to data from GP surgeries.
The charity claims the main cause behind the increased figures was the rise in obesity, in addition to family history and ethnic background as factors.
Type 2 diabetes is described by the NHS as “a common condition that causes the level of sugar (glucose) in the blood to become too high.”
Many of those with the illness are advised to change their diet and may require medication.
Image: The charity has backed calls for a ban on junk food TV advertising aimed at children before 9pm
Type 2 diabetes is more aggressive in young people. Complications from the disease, including blindness, amputations, heart disease and kidney failure can also appear earlier.
Around 1,500 people under the age of 19 are being treated for the illness, according to the figures which include patients at 95% of GP practices in England and Wales as well as in specialist paediatric units.
More than 5,380 people aged 20 to 24 are also receiving treatment.
Diabetes UK warned that thousands more children and young people could be diagnosed with the condition in the future.
The latest figures show that by the time they leave primary school, more than a third of children in England will be overweight or obese,
The charity has called for better specialist support for young people with the condition and backed calls for a ban on junk food TV advertising aimed at children before 9pm.
They also support proposals to restrict price promotions for unhealthy foods.
Bridget Turner, director of policy and campaigns at Diabetes UK, said: “Type 2 diabetes can be devastating for children and young people.
“To help shape a future where fewer children develop the condition, we need continued commitment across society to create an environment that reduces obesity.”
A Department of Health and Social Care spokeswoman said: “We are committed to halving child obesity by 2030 and 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.”