October 21, 2016

expert reaction to study looking at soft drinks and diabetes

Publishing in the European Journal of Endocrinology a group a scientists have examined the effect of sweetened and artificially sweetened drinks on type 2 diabetes and latent autoimmune diabetes in adults (LADA) and report that increased consumption was associated with an increased risk of the disease.

Dr Nita Forouhi, MRC Programme Leader, MRC Epidemiology Unit, University of Cambridge, said:

“The link between sweetened beverages and type 2 diabetes (but not type 1 diabetes or LADA) has been consistently shown across different countries, including our own previous research in 8 European countries in the InterAct Study and our systematic review of the world literature on this topic. This current study reports a link with a rare form of diabetes, LADA, which has features in common with both type 1 and type 2 diabetes. We should interpret the results of this study with caution. Increased thirst is a classical feature of diabetes onset, so higher intakes of beverages in the period leading up to a diagnosis of diabetes is to be expected. Therefore the higher beverages intake may well be the consequence rather than the ‘cause’ of diabetes onset, or ‘reverse causation’ in other words.

“This study had a case control design, and participants were asked to report their intake of sugar sweetened and artificially sweetened beverages by recall retrospectively one year prior to diagnosis. The authors conducted a sensitivity analysis to try to reduce reverse causation, but in fact this included restricting their analysis to diabetes cases who participated within six months of diagnosis. This may have in fact increased the potential for reverse causation, as symptoms of diabetes likely increase progressively until diagnosis, and thus those with the yet undiagnosed diabetes may have been drinking a lot of beverages to quench their thirst. The authors did include an analysis between water consumption as a marker of increased thirst during the year before diagnosis, but the overall findings need careful understanding, mechanisms and explanation.”

Prof. Christine Williams, Professor of Human Nutrition, University of Reading, said:

“The findings from this study are very interesting with the authors indicating that diets containing sweetened and artificially sweetened beverages were associated with an increased risk of type 2 diabetes (and of a rarer form of adult diabetes that has features of both juvenile and adult forms). The effect they report is large – with a 2-3 fold increased risk of diabetes for those who report drinking more than two sweetened beverages per day. Even when the findings were adjusted to account for other factors that could explain the findings, such as greater energy intake, higher BMI or poor diet, the risks remained significantly higher for the higher intake groups.

“A most interesting finding was that the higher risk was the same for both sweetened and artificially sweetened beverages, suggesting that greater risk of diabetes was not directly related to higher calorie intake, or adverse metabolic effects of sugar (in the form of sucrose) from the sweetened drinks.

“The study suffers from the same limitations as apply to most association studies. Even after controlling for effects of many other possible factors, including poor diet and heavier body weight, it is not possible to conclude that sweetened beverages are the direct cause of the relationship they have shown. One possibility they did not account for is that individuals who use sugar or artificial sweeteners in beverages have a higher craving for sweet foods generally and this could result in diets that are higher in sucrose. Although they accounted for ‘poor diet’ by controlling for lower intakes of healthier foods, they did not account for the possibility of higher intakes of sweet foods in their groups.

“Furthermore the well-known problem of under reporting (subjects self-reporting lower intakes of foods they know to be less healthy) is known to be more common in overweight and obese individuals. The diabetic subjects in this study were heavier than the control subjects. This raises the issue that although the body weight values themselves can be taken into account using statistical methods, the possibility that the diet records were biased due to greater under reporting in the diabetic group cannot be accounted for.

“Although they attempted to consider underlying mechanisms which could account for adverse effects of both sweetened and artificially sweetened beverages, no clear mechanism was put forward to explain their interesting, but provisional, observational findings.”

Dr Elizabeth Robertson, Director of Research at Diabetes UK, said:

“This study associated consuming two or more sugary or artificially sweetened drinks a day with increased risk of developing Latent Autoimmune Diabetes in Adults (LADA) and Type 2 diabetes. However, participants who drank more sweetened drinks also led unhealthier lifestyles in general, meaning a number of other factors like diet and exercise may have affected the results.

“More research is needed to determine the relationship between sweetened drinks and the risk of developing LADA and Type 2 diabetes.”

‘Sweetened beverage intake and risk of latent autoimmune diabetes in adults (LADA) and type 2 diabetes’ by Josefin E Löfvenborg et al. published in the European Journal of Endocrinology on Friday 21 October 2016. 

Declared interests

Dr Nita Forouhi: “No conflict of interest.”

Prof. Christine Williams: “Chair of the Board of Trustees and Governor, British Nutrition Foundation; Non-executive Director Scottish Rural University College (SRUC) Board; Member Rank Prize Nutrition Advisory Panel; Chair, BBSRC Agriculture & Food Security Strategy Panel and Research Advisory Board; Member Governing Body of the Institute of Food Research, Norwich; Member Scientific Advisory Council for Wales; Member European Food Information Council Scientific Advisory Group.”

No others received.