One in 10 adults over the age of 40 in the UK is living with a Type 2 diabetes diagnosis, analysis suggests.
Millions of cases could be avoided if people understood their risk of developing the largely preventable condition, Diabetes UK said.
The charity, which carried out the research, estimates 3.8 million people in England, Wales, Scotland and Northern Ireland have a diabetes diagnosis.
Around 90% are believed to be Type 2, which can be linked to excessive weight and obesity.
Nearly a million more people are estimated to be living with Type 2 but do not know they have it, Diabetes UK said.
By 2030, it estimates the number of people with diabetes will have risen to 5.5 million.
“Millions of Type 2 diabetes cases could be prevented if we help people understand their risk and how to reduce it,” said Chris Askew, chief executive of Diabetes UK.
“Even though the older people get the more likely they are to have Type 2 diabetes, it is never too early to know your risk so that you can make changes to prevent or delay it.
“The signs of Type 2 diabetes are often not obvious, that’s why spotting them early can be life-changing.
“Early diagnosis means that fewer people will experience diabetes-related complications such as sight loss, amputation, kidney failure, stroke and heart disease, because they could seek support to manage their condition effectively as soon as possible.”
Symptoms of Type 2 diabetes include feeling thirsty, going to the toilet frequently, and feeling more tired than usual.
Diabetes UK is urging people over the age of 40 to go for a free NHS Health Check when they are invited, and to check their risk of developing Type 2 diabetes using the charity’s online tool.
Professor Jonathan Valabhji, national clinical director for diabetes and obesity at NHS England, said: “The growing obesity epidemic is dangerous for the nation’s overall health and worrying for the NHS, fuelling growing numbers of people with Type 2 diabetes as well as costing taxpayers billions every year.
“This is exactly why the NHS Long Term Plan sets out radical action to tackle this growing problem by expanding the NHS Type 2 Diabetes Prevention Programme, so that 200,000 people every year can benefit, and introducing a pilot of very low calorie diets that have been shown to put Type 2 diabetes into remission in a significant proportion of those that already have it.”