Prediabetes is diagnosed by doctors when blood glucose is in danger of reaching type 2 diabetes levels.
The number of people in England with prediabetes trebled in the eight years to 2011.
One in three adults have the condition in the UK, according to Diabetes.co.uk.
But, making dietary changes and doing more physical exercise could return blood sugar levels back to normal.
Those with prediabetes don’t usually notice any symptoms, as the condition develops gradually.
Some patients are only diagnosed with the condition after type 2 diabetes symptoms begin to develop. These include blurred vision, fatigue, sudden weight loss, urinating more often than normal, often feeling hungry, and having an unquenchable thirst.
Diabetes patients are also at greater risk of strokes. In turn, this means prediabetes patients were at greater risk, too.
A study from the University of Belgrade this year said: “More than two thirds of prediabetes patients go on to develop type 2 diabetes.
“Prediabetes patients have an increased risk of cardiovascular diseases, including transient ischemic attack, stroke, and recurrent stroke.”
Those most at risk of developing prediabetes are those that are overweight, or have high blood pressure.
Having a close relative who currently has, or had diabetes also increase the risk.
In the same way as diabetes, prediabetes can be diagnosed with a fasting plasma glucose test, or an HbA1c test.
It is possible to avoid a type 2 diabetes diagnosis if you have prediabetes.
Last month, it was revealed that a third of prediabetes patients avoided type 2 diabetes by following a Weight Watchers eating regime.
About 90 per cent of all diabetes cases are type 2 diabetes.