'Politicians need to step up to the plate and be brave' / Getty

Treating diabetes and the complications arising from it costs the NHS around £10 billion annually 

Tackling diabetes is “fundamental” to the future of NHS as the number of adults with the condition nears four million, Public Health England has warned.

Around 3.8 million adults in England now have diabetes, with at least 940,000 of those undiagnosed, new figures have revealed.

About 90 per cent of the cases are Type 2 diabetes, which is linked to being overweight and obese and therefore largely preventable, PHE, who released the data, said.

The other 10 per cent are Type 1, which usually develops in childhood and is often inherited.

Diabetes can lead to serious health complications including limb amputation, kidney disease, stroke and heart attacks. Treating the disease and the complications arising from it costs the NHS around £10 billion annually.

John Newton, chief knowledge officer at PHE, said: "The number of people with diabetes has been steadily increasing and tackling it is fundamental to the sustainable future of the NHS.

"Diabetes can be an extremely serious disease for those that have it and treating it and its complications costs the NHS almost £10bn a year.

"Developing Type 2 diabetes is not an inevitable part of ageing. We have an opportunity through public health to reverse this trend and safeguard the health of the nation and the future of the NHS."

The new Diabetes Prevalence Model was launched ahead of PHE's conference at Warwick University. It shows that 9 per cent of people aged 45 to 54 have diabetes, but this rises to 23.8 per cent of those aged over 75.

Earlier this month, senior health officials warned that smokers and obese people will be denied surgery on the NHS by cash-strapped hospital trying to save money.

Vale of York Care Commissioning Group announced it will make people wait up to a year for non-essential surgery if they are overweight, until their body mass index (BMI) drops to 30, saying the decision was “the best way of achieving maximum value from the limited resources available”.

Across the entire UK, the number of people with diabetes has exceeded four million mark for the first time, the charity Diabetes UK said using GP practice data.

Chris Askew, chief executive of Diabetes UK, said of the new data: "These new estimates clearly show the scale of diabetes and the huge impact on people living with the condition.

"Too often they only find out they have the disease after they have developed serious complications, such as heart or kidney disease, or foot problems which can lead to amputations.

"Avoiding or delaying such devastating complications depends on people getting diagnosed earlier, so they get help and support to manage their condition well."

Additional reporting by Press Association