April 25, 2013

expert reaction to new research into sugary drinks and risk of developing type 2 diabetes

A study in the journal Diabetologia suggested drinking one sugar-sweetened soft drink a day can be enough to increase the risk of developing type 2 diabetes by 22%.

Professor Nick Wareham, Unit Director, MRC Epidemiology Unit, University of Cambridge, who leads the InterAct study, said:

“This finding comes from the largest study of this issue in Europeans and adds to a growing global literature suggesting that there is a link between consumption of sugar-sweetened beverages, obesity and risk of development of type 2 diabetes. Together with observations from randomised controlled trials, this observation suggests that consumption of these beverages should be limited as part of an overall healthy diet.”

Professor Patrick Wolfe, Royal Society Research Fellow and Professor of Statistics at University College London, said:

“This study reports an association between consumption of sweet and sweetened drinks and increased incidence of type 2 diabetes in European adults.  Previous studies, focussing largely on North American populations, have also found evidence of an association.  The authors note that `the consumption of sweet beverages in Europe appears to be lower than in the USA, though it appears to be rising [13]’, and point out that ‘diversity of dietary patterns in Europe leads to a wide variation in sweet beverage consumption across different countries [13,15]’.  Given these differences, the authors are interested in seeing whether an analysis of European populations leads to comparable findings.  In essence, it does.

“Both this study and the North American studies (reviewed in [6]) are best interpreted as comparing ‘extremes’: persons who consume fewer than one drink per month with those who consume at least one per day.   (In the current study, only about 8 percent of the sample fell into this latter category.) Comparing these extremes, the current study and a summary analysis [6] of North American studies suggest that drinking one or more cans per day of sugary soft drinks is associated with about a 20 percent increased relative risk of type 2 diabetes, relative to people who drink fewer than one can per month. Of course, this doesn’t tell us anything about absolute risk, so to put this figure in perspective, consider that as of 2010 in the UK, overall type 2 diabetes incidence stood at about 4 percent of the adult population (http://www.diabetes.org.uk/Documents/Reports/Diabetes_in_the_UK_2010.pdf).

“We have to be careful when interpreting relative risk increases, because they don’t tell the whole story.  Consider two individuals who are otherwise very similar, except that one individual drinks fewer than one sugary soft drink per month and the other drinks at least one per day.  These studies give evidence that the latter person will be at a heightened risk of developing type 2 diabetes relative to the former – but if both individuals are physically fit and at a healthy weight, their absolute risks may be quite low, while if both are overweight and inactive, their absolute risks may both be fairly high.  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.  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.

“Interestingly, the authors also saw an effect for diet soft drinks – but this effect disappeared when body mass index (BMI) and caloric intake were taken into account.  This suggests that diet soft drinks may not trigger the same mechanisms as sugary soft drinks, but that switching to diet soft drinks isn’t a panacea if you’re not also watching your weight.  By contrast, the increase in relative risk associated with drinking one or more can per day of sugar-sweetened soft drinks was still present even when BMI and caloric intake were taken into account – suggesting that the sugary-soft-drink effect is not due just to weight gain from ’empty calories’ but may also reflect other mechanisms such as insulin resistance.

“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.”

‘Consumption of sweet beverages and type 2 diabetes incidence in European adults: results from EPIC-InterAct’ by The InterAct Consortium, published in Diabetologia on Wednesday 24th April.