Are sugary drinks linked to diabetes?

Sugary drink illustration

“Cutting down by a can a day of fizzy drink could slash risk of contracting diabetes”

- The Sun, 1 May 2015

The BHF’s view:

This large study showed that cutting back on sugary drinks can reduce your risk of diabetes. Even swapping just one sugary drink a day for water or unsweetened tea or coffee could make a difference.

The University of Cambridge study looked at the effects of consuming sugar-sweetened drinks (such as fizzy drinks, hot chocolate and milkshakes), fruit juice, artificially sweetened drinks (such as ‘diet’ or ‘low calorie’ soft drinks) and unsweetened drinks.

Drinking sugar-sweetened drinks was linked to an increased risk of type 2 diabetes, and this increased the more sugary drinks were drunk. (The study did not look at type 1 diabetes, which is caused by a problem with the immune system not related to diet.)

Drinking unsweetened tea and coffee was linked to a lower risk of diabetes. Drinking sweetened tea/coffee, fruit juice, artificially sweetened drinks or water didn’t appear to affect the risk of diabetes either way on their own. But swapping a sugary drink for water or unsweetened tea/coffee, or swapping a sweetened hot drink for unsweetened, were both found to reduce the risk of diabetes.

Cutting down on sugary drinks is a simple swap that we can make to help improve our diets

There was already evidence for a link between diabetes and sugary fizzy drinks or squash, but this is the first time that a link with sweetened milk drinks had also been shown. This is also the first time that the effect of sugary drinks on diabetes across the population has been estimated. 

The study suggests that if everyone swapped one sugary drink a day for unsweetened tea/coffee or water, it could reduce new cases of type 2 diabetes by between 14 and 25%.

The study authors said: “Our findings suggest that reducing consumption of sweet beverages, in particular soft drinks and sweetened-milk beverages, and promoting drinking water and unsweetened tea or coffee as alternatives may help curb the escalating diabetes epidemic.”

This research was widely reported, including in the Express, Guardian, Mail, Sun (login only), and Telegraph. The media coverage was fairly accurate, although the Express headline, “A glass of water a day ‘can cut diabetes risk by a quarter’”, seems to suggest that it was water alone that had an impact on diabetes risk, when the study actually found results from reducing sugary drinks. 

The study looked at nearly 25,000 people aged 40 to 79 who were followed up for nearly 11 years, between the 1990s and 2006. The participants filled in daily food diaries of what they had eaten and drunk. This is a fairly accurate way of assessing this.

The main drawback of the study is that it is difficult to be certain that the effects seen were definitely caused by the drinks. The study authors did adjust the results to account for the effect of weight, social class, exercise and diet, but it is possible that some other factor could have affected the results.

BHF senior dietitian Victoria Taylor said: “We know that in the UK our intakes of sugar have exceeded dietary recommendations for some time. The sugar-sweetened drinks in our diet are one of the main sources.

“Consuming too much sugar is a problem because it can mean that we consume excess calories which is linked to overweight and obesity, a risk factor for both CVD and type 2 diabetes. While we can’t say from this study that it was the drinks that were the cause of the risk reduction for diabetes, it’s important not to forget the amount of sugar that can find its way into our diets from drinks as well as food.

“Cutting down on sugary drinks and replacing them with sugar-free options is a simple swap that we can make to help improve our diets.”

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