- Study on Diet Beverages and Type 2 Diabetes Has Serious Limitations
Study on Diet Beverages and Type 2 Diabetes Has Serious Limitations
ATLANTA (February 2, 2013) — The article “Consumption of artificially and sugar-sweetened beverages and incident type 2 diabetes in the Etude Epidémiologique auprès des femmes de la Mutuelle Générale de l’Education Nationale–European Prospective Investigation into Cancer and Nutrition cohort” is speculative and the results are not supported by robust clinical trials and laboratory studies. This new study does not prove that drinking diet beverages leads to diabetes; moreover, it is a study of only associations – no actual clinical testing was conducted. It is physiologically impossible for low-calorie sweeteners to cause diabetes.
The Calorie Control Council sites the following limitation:
- There were gaps in the study. Although the study ran from 1993 to 2007, the researchers only asked the participants how many diet beverages they drank over the course of the previous year once in 1993. What and how much subjects drank likely changed over the fourteen years of the study, although the authors did not account for it.
- The results are inconsistent with other research on aspartame. The authors suggested that aspartame might raise glucose or insulin levels, but over a dozen clinical studies have overwhelmingly shown that aspartame does not increase postprandial glucose or insulin levels. 2-14 It is extraordinary that the researchers did not discuss their findings in relationship to this work, which, again, includes robust clinical trials.
- The study was speculative. The authors suggested that low-calorie sweeteners may lead to increased preference for sweets and/or enhance appetite; however neither of these have been shown to be true in scientific studies. Rather, a recent review paper found that low-calorie sweeteners do not enhance appetite.15
- The study had numerous limitations. The association seen between diet beverages and diabetes was extremely weak. There was also a large variation in how much diet beverages the women consumed, which makes the data less accurate. The authors admitted they had “limited statistical power in some subcategories,” so the data is likely not reliable. Additionally, about 1 in 4 women in the cohort failed to participate, which has the potential to introduce self-selection bias. Finally, the questionnaire used in the study was only administered every 2-3 years which could introduce significant recall bias.
- The study cannot determine cause and effect. This study was observational, so it was designed to show an association, not prove cause and effect.
- Other factors may have influenced the findings. Although researchers tried to control for many variables, it is entirely possible that the findings were due to other factors for which the study was not controlled. This includes, for example, the actual diets of the participants during the years since 1993, the only time the participants were asked about their intake of diet beverages. The authors also failed to control for risk factors associated with Type 2 diabetes such as metabolic syndrome, hypertriglyceridemia, obesity, and coronary artery disease. External factors, such as these, likely influenced the results, as the authors admitted, “some confounders may still have been unmeasured.”
- The study findings were illogical. It is physiologically impossible for low calorie sweeteners to cause diabetes, and the authors offered no explanations as to why such an association might exist. Middle-aged people are more likely to develop type 2 diabetes regardless of what they drink, which is also commonly related to overweight. When the researchers controlled for body mass index (BMI), a measure of body weight, the association between diet beverages and diabetes decreased. This points to the possibility that the results reported may be related to factors unrelated to diet beverage use, such as total body fat. Type 2 diabetes is strongly associated with being overweight. Individuals seeking to lose weight or manage their blood sugars often switch to diet beverages. Low-calorie sweetener use might therefore simply be a marker for individuals already on weight-gain or diabetes trajectories, which continued despite their switching to diet beverages. This is the most plausible explanation of these findings, not that the diet beverages caused the overweight or diabetes.
Low-calorie sweeteners are some of the most thoroughly studied food ingredients in the food supply. The safety of low-calorie sweeteners has been reaffirmed time and again by leading health and regulatory groups worldwide. Further, leading health groups such as the Academy of Nutrition and Dietetics and American Diabetes Association support the safe use of low-calorie sweeteners.16-17 For more information about low-calorie sweeteners, visit: caloriecontrol.org.
Fagherazzi et al. Consumption of artificially and sugar-sweetened beverages and incident type 2 diabetes in the Etude Epidémiologique auprès des femmes de la Mutuelle Générale de l’Education Nationale–European Prospective Investigation into Cancer and Nutrition cohort. American Journal of Clinical Nutrition. 2013.
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