The incidence of type 2 diabetes—once called adult onset diabetes—is on the rise, and a frightening trend is that it’s afflicting people at ever younger ages, and even many children.
While it’s well known that obesity is a risk factor for developing type 2 diabetes, as are genetic factors, researchers have been trying to find out whether specific foods, such as sugars or fats, are correlated with type 2 diabetes independently of their role in causing obesity—in other words, is it only how much one eats, or also what one eats that determines type 2 diabetes risk?
A recent study published in the Archives of Internal Medicine looked at the relationship between consumption of sweetened soft drinks and fruit drinks, and type 2 diabetes in a large group of African American women. The incidence of diabetes in African American women is twice that of white women, which makes finding modifiable diet factors even more important in this subpopulation.
The study included 43,960 women from all parts of the U.S. This group filled questionnaires about dietary habits, height, weight, demographic characteristics, lifestyle factors and other exposures, medical history, and other factors, and was followed for 10 years.
These were the main findings:
• 2,713 participants developed diabetes during the ten years of follow-up.
• The incidence of type 2 diabetes rose with an increasing intake of both sugar-sweetened soft drinks and fruit drinks.
• Women who consumed two or more soft drinks a day had a 24 percent increase in incidence of diabetes relative to women who drank less than one soft drink per month.
• Women who consumed two or more fruit drinks a day had a 31 percent increase in incidence of diabetes relative to women who drank less than one per month.
• The majority of participants gained weight, but the greatest weight gain was seen in those women who increased their consumption of soft drinks.
• After controlling for increased weight (a known risk factor for diabetes) using the body-mass index, or BMI, a statistical measure of the weight of a person scaled according to height, the study showed that women who consumed two or more soft drinks a day had a 5 percent increase in incidence of diabetes relative to women who drank less than one soft drink per month, but women who consumed two or more fruit drinks a day had a 33 percent increase relative to women who drank less than one soft drink per month. What this data implies that there is additional risk to intake of sugars and HFCS (high fructose corn syrups) in the development of diabetes independent of overweight and obesity.
There was another thing I found very interesting in the results of this research: women who had a high intake of sugar sweetened soft drink were more likely to be younger, less physically active, have less education, have a high BMI, smoke, eat more red meat and processed meat and have a diet with a high glycemic index. (The glycemic index or GI is a measure of the effects of carbohydrates on blood glucose levels. Foods that are absorbed quickly like sugar and candy have a high GI; foods that take longer to break down and are absorbed slowly, like grainy bread, have a low GI.)
Women with a high intake of sugary fruit drinks were also more likely to be younger, and have a higher intake of both calories and processed meat, but fruity drink consumption was correlated with healthy behaviors such as higher rates of physical activity, a diet with more cereal fiber and a diet with a low glycemic index.
So, why are sugary drinks associated with diabetes?
The authors led by Julie R Palmer, discuss several possible mechanisms:
“The first, which probably accounts for most of the association, is through weight gain. A systematic review of the literature indicates a positive association between greater intakes of sugar-sweetened beverages and weight gain and obesity in both children and adults.
These beverages are dense in calories and are typically consumed as an addition to usual food intake. Several studies have shown that liquid foods have a low satiety and that when individuals increase consumption of liquid carbohydrates, they may not reduce consumption of solid food in response. High-fructose corn syrup, which is now the sweetener used in all sugar-sweetened soft drinks consumed in the United States, appears to be particularly effective at promoting weight gain because of its adverse effects on insulin secretion and leptin release, leading to a reduction in the normal inhibitory effect on food intake…
A second possible mechanism is through the glycemic effects of the beverages. Both sugar-sweetened soft drinks and fruit drinks contain large amounts of rapidly resorbed carbohydrates, the consumption of which leads to rapid increases in glucose and insulin concentrations. Although the literature is not consistent, several large studies have found a positive association between glycemic load of the diet and risk of type 2 diabetes.”
The take home message
I think it is still unclear whether high intake of sugars is associated with increased risk of developing diabetes independently of the extra calories that these drinks pack. Several studies have looked at that question, and while there are more studies showing a correlation (like this study), there are studies that do not.
This reminds me of the other debate that awaits clarification: Does high-fructose corn syrup contribute to overweight and obesity any differently than do other sugars like sucrose?
What’s for sure is that sugary drinks do have a lot of calories, and the rise in consumption of sugary drinks—which has been dramatic over the last few decades—correlates the expanding waistline of Americans and people worldwide.
Reducing the amount of calories from food one eats is hard, no matter which diet you follow. But, clearly, one of the easier ways to decrease total calories is to give up some, or all, of the sugary drinks one consumes.
They add nothing to your health, and add plenty of empty calories.
I’ll end with the last paragraph of the Archives of Internal Medicine paper (emphasis is mine):
“Finally, it should be noted that consumption of fruit drinks conveyed as high an increase in risk as did consumption of soft drinks. Fruit drinks typically contain as many or more calories compared with soft drinks and, like soft drinks, may not decrease satiety to the same extent as solid food. Fruit drinks were consumed more frequently than soft drinks in our study, and in the US population, the proportion of total energy intake from fruit drinks doubled from 1977 to 2001. The public should be made aware that these drinks are not a healthy alternative to soft drinks with regard to risk of type 2 diabetes.”