Obesity is usually cited as the main driver of diabetes. But a new study by US medical researchers identifies sugar as a predictor of diabetes separately from obesity.

The findings, published in the scientific journal Plos One, do not claim that sugar causes obesity. But they are significant because they pinpoint it as being closely associated with diabetes, a disease that at least 2.7 million Britons already have.

Researchers led by Sanjay Basu, an assistant professor at Stanford University school of medicine, examined the availability of sugar and diabetes rates from 175 countries worldwide over the last decade.

"We're not diminishing the importance of obesity at all, but these data suggest that at a population level there are additional factors that contribute to diabetes risk besides obesity and total calorie intake, and that sugar appears to play a prominent role," said Basu.