Drinking one can of soft drink a day can increase the risk of type 2 diabetes by a fifth, scientists warn.
A major study found the risk rose by as much as 22 per cent for every 12oz serving of sugar-sweetened drink – a typical can – consumed per day.
Soft drinks have previously been linked with weight gain and obesity – a well-known trigger for type 2 diabetes – but researchers say the effect goes beyond body weight and may be caused by an increase in insulin resistance.
The study of almost 30,000 people living in eight European countries, including Britain, follows US research which made near-identical findings. Scientists at Imperial College London wanted to determine whether the link held good in Europe, where soft drinks are less popular than in America.
Professor Nick Wareham, of the Medical Research Council’s epidemiology unit, who oversaw the study, said it was more evidence that people should be cautious about the amount of sugary soft drink they consumed.
He said: ‘This finding adds to growing global literature suggesting that there is a link between consumption of sugar-sweetened beverages, obesity and risk of development of type 2 diabetes.
‘This observation suggests that consumption of these beverages should be limited as part of an overall healthy diet.’
Researchers found that the risk of type 2 diabetes rose 22 per cent for people having one 12oz (336ml) serving of sugar-sweetened soft drink a day compared with those not having any. For those having two soft drinks, it rose a further 22 per cent over those having one drink.
The number of Britons diagnosed with diabetes hit three million this year for the first time – almost one in 20 of the population.
Type 2 diabetes is strongly linked to lifestyle factors such as being overweight or obese, leading a sedentary lifestyle and an unhealthy diet.
It occurs when the body gradually loses the ability to process blood sugar, leading to high levels which can damage body organs and result in years of ill-health.
The latest study used data on consumption of juices and nectars, sugar-sweetened soft drinks and artificially sweetened soft drinks. It involved 12,403 people with type 2 diabetes and 16,154 without diabetes.
The researchers, led by Dr Dora Romaguera, said a possible reason for the link could be the effect of sugar-sweetened drinks on insulin resistance.
Type 2 diabetes is frequently preceded by an increase in insulin resistance, where the body becomes insensitive to the effects of insulin resulting in high blood sugar levels.
Dr Romaguera said: ‘Given the increase in sweet beverage consumption in Europe, clear messages on the unhealthy effect of these drinks should be given to the population.’
Consumption of pure fruit juice and nectar drinks was not implicated in rising diabetes, although the study could not separate out the effect of 100 per cent pure juices from those with added sugars.
Dr Matthew Hobbs, of Diabetes UK, said: ‘The large number of people involved in this study means this finding is extremely unlikely to have happened by chance.’
Gavin Partington, of the British Soft Drinks Association, said: ‘It is well known that diabetes is the result of many different factors, including obesity and family history.
‘Soft drinks are safe to consume but, like all other food and drink, should be consumed in moderation.’ The study was published in Diabetologia, the journal of the European Association for the Study of Diabetes.