There are thought to be 850,000 people who don not know they have type 2 diabetes.
A record breaking three million people have now been diagnosed with the disease, and experts are warning unless more is done to prevent the condition, the NHS could become burdened with unsustainable costs.
Diabetes sufferer Lynda Marks said dealing with the condition is much easier once you start talking about it.
We are hugely concerned that the number of people diagnosed with diabetes has reached three million for the first time and there is no reason to think this will mark the end of what has been a rapid rise in the condition.
Instead, all the projections suggest that the three million figure will be a grim staging post on the road towards a public health emergency and this unfolding tragedy is already putting huge pressure on the NHS and will have potentially devastating consequences for those people who develop the condition. But this is not inevitable.
Three million Britons have been diagnosed with diabetes, research has shown.
It is the equivalent to 4.6 per cent of the population, and experts say the figure is growing, warning it was a "grim staging post towards a public health emergency".
Research by Diabetes UK and Tesco has found that more than 130,000 people were diagnosed with the disease over the last year, with an estimated 850,000 people thought to have undiagnosed Type 2 diabetes.
Health experts say that the NHS could be burdened with unsustainable costs, unless more is done to prevent it.