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Sweetened drinks greater risk for poor glycaemic control

Food source as well as energy content seem to play role in effect of fructose-containing sugars in diet

Louise Prime

Thursday, 22 November 2018

The effects on glycaemic control of consuming fructose-containing sugars appear to be dependent on food source as well as energy content, with sweetened drinks posing a much greater risk of type 2 diabetes than other food sources of fructose-containing sugars, especially fruit, researchers from Canada have concluded. In the light of their analysis*, published today in the BMJ, they called on those who make policy and guidelines to consider the influence of energy control and food source in their development of recommendations to reduce sugars for the prevention and management of diabetes.

The research team pointed out that there is active debate about the role of sugars – and particularly fructose – in the development of cardiometabolic disease, with links being drawn between the introduction in the 1970s of high fructose corn syrup as a popular sweetener, and global rises in obesity and diabetes prevalence. They decided to assess the effect glycated haemoglobin (HbA1c) levels, fasting blood glucose, and fasting blood glucose insulin of different food sources of fructose-containing sugars, at different levels of energy control, with a systematic review and meta-analysis of controlled intervention studies.

The 155 included studies, with a total of 5,086 participants, fell into four categories of design: substitution (comparing sugars with other carbohydrates), addition (energy from sugars added to diet), subtraction (energy from sugars removed from diet), or ad libitum (energy from sugars freely replaced).

The researchers reported that total intake of fructose-containing sugars had no harmful effect on any outcome in substitution or subtraction studies, and in fact a significant decrease was seen in HbA1c in substitution studies (mean difference −0.22%, −25.9mmol/mol); however, total intake had a harmful effect on fasting insulin in addition studies (4.68pmol/l) and in ad libitum studies (7.24pmol/l).

They also found that there was interaction by food source, with specific food sources showing beneficial effects (fruit and fruit juice) or harmful effects (sweetened milk and mixed sources) in substitution studies and harmful effects (sugars-sweetened beverages and fruit juice) in addition studies on at least one outcome.

The study authors commented that their findings might help guide recommendations on important food sources of fructose in the prevention and management of diabetes, but the current level of evidence is low.

They concluded: “More large, high quality studies using a greater variety of food sources of fructose-containing sugars are required to assess the durability of these effects and understand whether certain food sources with an apparent signal for benefit, such as fruit, might even have advantages for glycaemic control under free living conditions over the longer-term (six months or longer).

“Meanwhile, policy and guidelines makers should consider the influence of energy control and food source in the development [of] recommendations to reduce sugars for the prevention and management of diabetes.”


*Choo VL, Viguiliouk E, Meija SB, et al. Food sources of fructose-containing sugars and glycaemic control: systematic review and meta-analysis of controlled intervention studies. BMJ 2018; 363: k4644 doi: 10.1136/bmj.k4644.

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