An estimated seven million people in the UK have early warning signs of diabetes, researchers warned today.
The condition - called prediabetes - means their blood sugar is higher than normal and makes them up to 15 times more likely to develop full blown Type 2 diabetes, charity Diabetes UK said.
Many of those at risk are overweight or obese, have a family history of prediabetes or have high blood pressure and cholesterol.
The charity said prediabetes could be countered by losing weight, upping physical activity levels and adopting a healthier diet. This in turn reduces the risk of developing the full-blown version by 60%.
Recent figures show that more than 145,000 new cases of mainly Type 2 diabetes were diagnosed in the past year, bringing the total number of people with diabetes in the UK to 2.6 million.
Diabetes UK chief executive Douglas Smallwood is calling on people to be more aware of their health.
He said: "It's staggering that seven million people in the UK have prediabetes, which is often a precursor to Type 2 diabetes, a serious condition which can lead to long term complications such as heart disease, stroke, kidney failure, amputation and blindness.
"Identifying and educating people with prediabetes is vital as it's not too late for many to make healthy lifestyle changes, reverse the condition completely and reduce their risk of developing type 2 diabetes."
Diabetes is where the body produces too much blood sugar.
Type 1 usually develops in childhood and sees sufferers requiring insulin injections as soon as they are diagnosed.
Type 2 is linked to obesity and inactive lifestyles and managed by diet, drugs or insulin injections.