Two fizzy drinks a day could double the risk of diabetes - even if they are diet versions - a Swedish study has found.

Research by the Karolinska Institute on 2,800 adults found that those who consumed at least two 200ml servings of soft drinks daily were 2.4 times as likely to suffer from a form of type 2 diabetes.

Many fizzy drinks are sold in 330ml cans, meaning that one and a half cans would be enough to double the risk.

Those who drank a litre of such drinks saw a 10-fold rise in their chance of suffering from the condition.

The increased risks were the same regardless of whether the drinks were sugary or artificially sweetened, the research published in the European Journal of Endocrinology found.

Researchers said the sugary drinks may have induced insulin resistance, triggering the cases of diabetes.