Figures suggest that one million people in England are living with undiagnosed type 2 diabetes.
Survey data suggests seven per cent of those aged 16 and over show evidence of the disease, but a third are undiagnosed, according to the Office for National Statistics (ONS).
Younger people with this condition, which causes blood sugar levels to be too high, were more likely to go undiagnosed.
People who have type 2 diabetes were also less likely to be diagnosed if they were in good health.
The charities called the figures “shockingly high” and urged those with symptoms to get tested and treated as soon as possible to avoid “devastating complications”.
Almost 4.3 million people were living with diabetes in 2021/22, according to the latest UK figures. And another 850,000 people have diabetes and are completely unaware of it, which is worrying because untreated type 2 diabetes can lead to complications such as heart disease and stroke.
Symptoms of this condition, which is diagnosed with a blood test, include excessive thirst, tiredness, and the need to urinate more frequently. But many people have no signs
The ONS findings were based on the Health Survey for England from 2013 to 2019, which asks around 8,000 adults and 2,000 children about their health each year. Blood and saliva samples are taken.
In total, 999,700 people are believed to have undiagnosed type 2 diabetes, while an estimated 5.1 million have prediabetes.
Half of people aged 16 to 44 were undiagnosed compared to 27 per cent aged 75 and over, the ONS said.
People with type 2 diabetes in good general health were also more likely to go undiagnosed, as were thin women with smaller waists who were not prescribed antidepressants, it found.
ONS figures also showed that prediabetes (when blood sugar levels are higher than usual but not high enough to diagnose diabetes) affects around 5.1 million adults in England.
Those most likely to develop the condition had known diabetes risk factors, such as being overweight or older.
However, the ONS said there was a “considerable prevalence” in people considered at low risk of prediabetes, including 4 per cent of people aged 16 to 44 and 8 per cent who were not overweight or obese.
People from black or Asian groups also faced more than double the risk of prediabetes (22 percent), compared to 10 percent of people from white, mixed and other ethnic groups.
Type 2 diabetes overall was highest among black and Asian people, at 5 percent.
An analysis by the charity Diabetes UK in 2023 estimated that 4.3 million people were living with a diabetes diagnosis in the UK.
It previously estimated that 850,000 were undiagnosed, based on diabetes prevalence models and projections produced by Public Health England in 2016.
Type 2 diabetes occurs when the body does not produce enough insulin, which is necessary to lower blood sugar levels.
Having high blood sugar levels over time can lead to heart attacks and strokes, as well as eye, kidney, and foot problems.
Sufferers may need to review their diet, take daily medications, and have regular checkups.
Symptoms of this condition, which is diagnosed with a blood test, include excessive thirst, tiredness, and the need to urinate more frequently. But many people have no symptoms.
Nikki Joule, policy director at Diabetes UK, said: “Type 2 diabetes is a life-changing disease that often develops slowly, especially in the early stages when it can be very difficult to detect symptoms.”
He added: ‘Figures published today by the ONS reveal a shockingly high number of people living with type 2 diabetes without a diagnosis, while millions more are at high risk of developing it.
“We are particularly concerned about the prevalence of prediabetes and undiagnosed type 2 diabetes in people of black and Asian origin, and the worrying proportion of younger people who are undiagnosed, as we know that type 2 diabetes is more aggressive in people younger.
“The findings are a reminder of how important it is that type 2 diabetes is detected and diagnosed as early as possible, so that people can receive treatment and support to reduce the risk of devastating complications and, most importantly, offer them referral programs when necessary. .’