Diabetes is defined by the inability to regulate blood sugar levels, but sugar was thought to have only an indirect role in development of the disease, by triggering obesity.
Now scientists have found that people with large amounts of sugar in their diet are more likely to develop diabetes even when other factors, such as obesity and calories from other sources, are accounted for.
Researchers believe sugar may have a 'prominent role' in the development of diabetes and could account for differences in diabetes rates that cannot be explained by obesity.
They said the findings support other research showing sugar can affect the liver and pancreas in different ways to obesity or other food types.
The researchers looked at data on sugar availability and diabetes rates from 175 countries in the past decade. After accounting for obesity, they found the amount of sugar in a nation's diet was directly associated with diabetes rates.
For every 150 calories of sugar available per person per day, diabetes prevalence rose 1%, even after accounting for obesity, physical activity, alcohol intake and different calorie types. When sugar availability dropped, diabetes rates also fell.
Study lead Dr Sanjay Basu from Stanford University in California said: 'We're not diminishing the importance of obesity, but these data suggest that at a population level, additional factors contribute to diabetes risk and sugar appears to play a prominent role.'