The number of people with diabetes is expected to reach 4.4 million by 2020 as the obesity epidemic takes its toll, a charity has warned.
Over the next eight years the number of people in Britain with the condition is expected to increase by 700,000, according to Diabetes UK.
The charity said that the rise in the number of people with the condition will put a significant financial strain on the NHS - which is already spending 10% of its budget on treating people with diabetes.
Chief executive Barbara Young said a combination of diabetes and NHS budget pressures could create a "perfect storm that threatens to bankrupt the NHS".
The charity, which analysed figures from the Yorkshire and Humber Public Health Observatory, said the vast majority of new cases will be Type 2 diabetes - which is linked to unhealthy lifestyles and obesity.
Type 2 diabetes, which accounts for 90% of all cases, is a long-term condition that occurs when the body does not produce enough insulin for it to function properly, or when the body's cells do not use insulin properly.
Diabetes UK said that at present around 3.7 million people in Britain have diabetes, including an estimated 850,000 people who have Type 2 diabetes but do not know it.
It is calling for the Government to fund a public health campaign to raise awareness about the condition, which can cause blindness, kidney failure, stroke and amputation.
Ms Young said: "The healthcare system is already at breaking point in terms of its ability to provide care for people with diabetes and the result is that many people are developing health complications that could have been avoided and are dying early as a result.
"We face the very real prospect of the rise in the number of people with the condition combining with NHS budget pressures to create a perfect storm that threatens to bankrupt the NHS.
"If this projected increase becomes reality, it would be a calamity for the healthcare system and a disaster for public health. But the Government and the NHS do not seem to have grasped the scale of the impending crisis and at the moment we seem to be sleepwalking towards it. But the crucial point is that it is still not too late to take the action needed to avert it.
"We need a Government-funded campaign to raise awareness of risk factors for Type 2 diabetes to help identify and give proper support to those at high risk and to highlight the seriousness of the condition so that people understand why they should be doing everything they can to prevent it.
"We still hear about people who think diabetes is a relatively mild condition and do not realise it can lead to devastating complications such as blindness, amputation and stroke."
The charity said that Type 1 diabetes, which develops when the body cannot produce any insulin, is also rising but scientists do not know for sure why this is the case.
A Department of Health spokesman said: "We are taking wide-ranging action to tackle diabetes. First through prevention - by encouraging healthier lifestyles and identifying those at risk and supporting them to take the necessary action to prevent diabetes. Secondly, by better management of the condition, both in hospital and in the community.
"We hope to help prevent people getting diabetes in the first place, but by investing in the NHS and modernising it, we will also drive up the quality of care for those who have the disease."