A blood test developed by a scientist reveals whether you are at risk of diabetes 10 years before symptoms show up.

By measuring levels of five markers in the blood, doctors are able to predict the onset of type 2 diabetes, which already affects more than 220 million people worldwide.

The test could act as an early warning for those most at risk - giving them time to improve their diet or change their lifestyles, the journal Nature Medicine reports.

Thomas Wang, who developed the test at the Massachusetts General Hospital in the US, said: `These findings could provide insight into metabolic pathways that are altered very early in the process leading to diabetes,` the Daily Mail said.

All you need to know about Type 1 diabetes

Diabetes occurs when the pancreas is unable to produce enough insulin - the hormone that controls blood sugar - or when its insulin does not work properly.

Wang and colleagues looked at blood samples from 189 diabetics before they developed symptoms of the disease and compared them to blood from 189 healthy people.

After measuring levels of 61 metabolites, by-products of metabolism, they discovered five amino acids that were higher in the people who developed diabetes.