One in three adults in England 'on cusp' of diabetes
More than a third of adults are on the cusp of developing type-2 diabetes, figures for England show.
A report, in the British Medical Journal, highlights an "extremely rapid" rise in pre-diabetes since 2003.
The authors predict a surge in type-2 diabetes in the coming years, with consequences for life expectancy and disability.
The charity Diabetes UK said the NHS was already spending one-tenth of its budget on the condition.
People with pre-diabetes have no symptoms of ill health, but their blood sugar levels are at the very high end of the normal range - on the cusp of diabetes.
Between 5% and 10% of people with pre-diabetes go on to develop type-2 diabetes each year, the researchers said.
Their study looked at Health Survey for England data between 2003 and 2011.
In 2003, 11.6% of adults surveyed had pre-diabetes, but the figures trebled to 35.3% by 2011.
Case study - Helen Barker
Three years ago, 39-year-old Helen Barker from Snaith in East Yorkshire was told she was following her brother and her dad on the path to type-2 diabetes.
"It was through a routine check-up at the doctors, I was told my glucose tolerance was not at the right levels."
She was advised to change her lifestyle and went on to improve her diet, exercise more and initially dropped five stone.
"It worked, to be completely honest I put some weight back on, but I'm in a lot different place now, I was retested and I'm back to normal.
"I don't want to be back in that category, my dad's got so many health problems because of diabetes."
He cannot drive due to damage to his eyes and is about to start kidney dialysis.
Helen said: "There are simple steps to turn things around, if only he'd known 10 years sooner that he could have prevented some of these things."
Prof Richard Baker, one of the report's authors from the University of Leicester, told the BBC: "The level of increased diabetes risk has gone up quite steeply, it has been rising in other countries, but it has leapt up faster in England than in the US - it's a big jump really.
"A lot of people with type-2 diabetes manage their condition very well, but some are unlucky and get severe consequences quickly, it's not a nice disease to have."
Fellow researcher Dr Arch Mainous, from the University of Florida, added: "I think the huge rise was surprising, it was substantial.
"People are going to transition from these high-risk states to diabetes and there will be a lot of implications for people being sick and healthcare costs."
- Blood vessel damage increases the risk of heart attacks and stroke
- Nerve damage
- Foot ulcers, potentially leading to amputation
- Kidney damage
- Impaired sexual performance
- Increased risk of miscarriage
Prof Baker said the health service had some good things in place, such as health checks for people over the age of 40.
But he argued a broader approach "either more regulation or getting the food industry to compete more on the healthiness of their products" was needed.
Around 3.2 million people in the UK have type-2 diabetes and the charity Diabetes UK estimates that figure will rise to 5 million by 2025.
The condition is linked to risk factors which include being overweight.
Type 2 diabetes develops when the insulin-producing cells in the body are unable to produce enough insulin, or when the insulin that is produced does not work properly.
The charity's chief executive Barbara Young said: "Unless we make people aware of their risk of type-2 diabetes and support them in changing their lifestyles, we could see an even greater increase in the number of people with the condition than we are already expecting.
"A tenth of the NHS budget is already being spent on diabetes and unless we get much better at preventing type-2 diabetes this spending will soon rise to unsustainable levels."
"Up to 80% of cases of type-2 diabetes could be avoided or delayed.
"Programmes such as the NHS Health Check are already doing an important job in assessing people's risk, by measuring weight and waist, as well as looking at family history and ethnicity.
"But at the moment not everyone who is eligible for this check is getting one and we need this to change."