Just one can of sugary soft drink raises the relative risk of diabetes by around a fifth, a study has found.
Every extra can consumed a day increased the chances of having the disease by 22%, compared with drinking one can a month or less.
The increase in risk only fell slightly after adjusting the findings to take account of body mass index (BMI).
This suggests it was not simply being overweight that led to the trend, said the researchers.
Sugar-sweetened drinks appeared to have an effect on the body unrelated to obesity.
The results of the study conducted in the UK and eight other European countries broadly mirror previous findings from mostly American research.
A total of 350,000 individuals were questioned about their diet, including their consumption of sugar-sweetened and artificially sweetened “lite” soft drinks and juices.
All were participants in the European Prospective Investigation into Cancer and Nutrition (Epic) study looking at links between diet and cancer.
Incidence of Type-2 diabetes was compared with consumption of 12 fluid ounce servings of sweetened drinks, equivalent to a normal-sized can of Coca-Cola.
A statistically significant association was seen between high sugary drink consumption and Type-2 diabetes risk.
The disease occurs when the body stops responding properly to the hormone insulin, leading to rising blood sugar levels. Unlike Type-1 diabetes it is lifestyle-related and not an auto-immune condition.
The scientists, led by Dr Dora Romaguera, from Imperial College London, wrote in the journal Diabetologia: “This study corroborates the association between increased incidence of Type-2 diabetes and high consumption of sugar-sweetened soft drinks in European adults..
“Given the increase in sweet beverage consumption in Europe, clear messages on its deleterious effect on health should be given to the population.”
An increased risk of diabetes was also linked to consumption of artificially sweetened soft drinks, but the association faded away when BMI was taken into account.
In this case, it looked as if body weight was responsible for the trend rather than the drink itself.
Fruit juice consumption was not associated with diabetes incidence.
Commenting on the results, statistics expert Professor Patrick Wolfe, from University College London, stressed the importance of putting the results in perspective. He pointed out that the absolute risk of Type-1 diabetes was low at around 4% of the adult UK population.
“In and of themselves, sugary soft drinks are only part of the picture - they’re just one of the potential risk factors for Type-2 diabetes,” he said. “But since they are one we can easily eliminate - by switching to diet soft drinks or, even better, cutting them out of our diets altogether - it makes good sense to do so.
“The bottom line is that sugary soft drinks are not good for you - they have no nutritional value and there is evidence that drinking them every day can increase your relative risk for Type-2 diabetes. But your overall likelihood of developing Type-2 diabetes will depend on your individual risk factors - primary among them your weight and level of physical fitness.”