One sugary drink a day raises diabetes risk by a fifth

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Drinking one can of fizzy drink a day can increase the risk of developing type 2 diabetes by a fifth, researchers have found.

The study has been welcomed by Otago University diabetes expert Professor Jim Mann, who says there is unquestionable evidence that sugary drinks are bad - but he has also cautioned against taking the can-a-day finding too literally.

Researchers from Europe's InterAct consortium looked at the consumption of juices, sugar-sweetened soft drinks and artificially sweetened soft drinks among 350,000 people in Europe.

They found that with the daily consumption of 365mls of sugar-sweetened soft drink - which is just over one standard 330ml can of fizzy drink - the risk of type 2 diabetes increased by 22 per cent.

The risk fell slightly to 18 per cent after accounting for total energy intake and body-mass index, which suggested the effect of sugary drinks on diabetes was not down to body weight alone.

Researchers found drinking pure fruit juice was not associated with diabetes risk.

Dr Mann, director of the Edgar National Centre for Diabetes Research, said the study was further evidence that sugary drinks were bad.

But he cautioned against taking the study's can-a-day finding too literally, saying it was difficult to disentangle the risk of diabetes from obesity.

"If we are too literal about our interpretation of these things ... there's a danger that the results are rubbished, when actually the real bottom line is that there is unquestionable evidence that sugary drinks are not good and we need to restrict them.

"And yes, even one sugary drink probably has some effect, but I'm a little bit nervous of making too much of the precise number, when actually there's confidence intervals attached to that number.''

The study's lead author, Dr Dora Romaguera of Imperial College London, said the increased risk of type 2 diabetes among soft drink consumers in Europe was similar to that in North America - where the risk was 25 per cent for each sugar-sweetened soft drink consumed a day.

"Given that people are drinking more and more sugary drinks in Europe, we need to give out clear messages about their harmful effects.''

The study was published in Diabetologia, the journal of the European Association for the Study of Diabetes.