Study Links Sugary Beverages With Increased Risk of Diabetes

The findings showed that drinking one to two sugary drinks per day increased the risk of type 2 diabetes by 26% and the risk of metabolic syndrome by 20% compared with those who consumed less than one sugary drink per month.

Oct 28 2010 --- A new study has found that regular consumption of soda and other sugar-sweetened beverages is associated with a clear and consistently greater risk of metabolic syndrome and type 2 diabetes. According to the Harvard School of Public Health (HSPH) researchers, the study provides empirical evidence that intake of sugary beverages should be limited to reduce risk of these conditions.

The study appears online October 27, 2010, in the journal Diabetes Care and will appear in the November print edition.

"Many previous studies have examined the relationship between sugar-sweetened beverages and risk of diabetes, and most have found positive associations but our study, which is a pooled analysis of the available studies, provides an overall picture of the magnitude of risk and the consistency of the evidence," said lead author Vasanti Malik, a research fellow in the HSPH Department of Nutrition.

Consumption of sugary drinks, the majority of which are sodas, has increased substantially in the U.S. and across the globe and previous scientific studies have shown consistent associations with weight gain and risk of obesity. However, this study is the first meta-analysis to quantitatively review the evidence linking sugar-sweetened beverages with type 2 diabetes and metabolic syndrome. (Metabolic syndrome is a group of risk factors, such as high blood pressure and excess body fat around the waist, that increase the risk of coronary artery disease, stroke and diabetes.)

The researchers, led by Malik and senior author Frank Hu, professor of nutrition and epidemiology at HSPH, did a meta-analysis that pooled 11 studies that examined the association between sugar-sweetened beverages and those conditions. The studies included more than 300,000 participants and 15,043 cases of type 2 diabetes and 19,431 participants and 5,803 cases of metabolic syndrome.

The findings showed that drinking one to two sugary drinks per day increased the risk of type 2 diabetes by 26% and the risk of metabolic syndrome by 20% compared with those who consumed less than one sugary drink per month. Drinking one 12-ounce serving per day increased the risk of type 2 diabetes by about 15%.

"The association that we observed between soda consumption and risk of diabetes is likely a cause-and-effect relationship because other studies have documented that sugary beverages cause weight gain, and weight gain is closely linked to the development of type 2 diabetes," said Hu.

While a number of factors are at work in the development of type 2 diabetes and metabolic syndrome, sugar-sweetened beverages represent one easily modifiable risk factor that if reduced will likely make an important impact, say the researchers. "People should limit how much sugar-sweetened beverages they drink and replace them with healthy alternatives, such as water, to reduce risk of diabetes as well as obesity, gout, tooth decay, and cardiovascular disease," said Malik.

Other HSPH authors include Walter Willett, chair of the Department of Nutrition and Frederick John Stare professor of nutrition and epidemiology.

There was no funding for this study and the authors report no conflicts of interest.

In response to "Sugar Sweetened Beverages and Risk of Metabolic Syndrome and Type 2 Diabetes: A Meta-analysis,", Dr. Maureen Storey, senior vice president for science policy for the trade association American Beverage Association, said:

"It is overly simplistic, and simply misleading, to suggest that reducing or eliminating sugar-sweetened beverages from the diet will uniquely lower incidence of serious health conditions such as diabetes or metabolic syndrome. After all, correlations found in epidemiological studies are not indicators of causality. In fact, there is a critical flaw in the design of the studies used in this meta-analysis in that the authors focus solely on the impact of one calorie source - sugar-sweetened beverages - on weight, rather than looking at all sources of calories.

Furthermore, medical experts agree that a primary risk factor for both diabetes and metabolic syndrome is obesity, something which can be mitigated by maintaining a healthy weight. And we know that the key to maintaining a healthy weight is balancing calories consumed, regardless of their source, with calories burned. Therefore, if anything, this paper only once again underscores the overall importance of a balanced, healthy and active lifestyle.

It's also important to recognize that, despite the authors' suggestion, sales of soft drinks have actually declined by nearly 12 percent since 2000, due in part to the beverage industry's innovation in bringing more no-calorie, low-calorie and smaller-portion beverage options to market. In fact, from 1998 to 2008, industry cut the total beverage calories it brought to market by 21 percent.

Regardless, there is nothing unique about the calories from sugar-sweetened beverages - calories that contribute only about 7 percent of the calories in the average American diet according to a National Cancer Institute analysis of government data. That means 93 percent of our calories come from other sources. Furthermore, when it comes to diabetes, a report issued just last week by the Centers for Disease Control and Prevention also reinforced the importance of diet and physical activity in reducing risk, not singling out any one food or beverage for reduction or elimination from the diet.

If we truly want to lower the risk of obesity-related health conditions, we need to focus on nutrition education, access to information and physical activity. These are areas our industry supports and encourages by offering a wide variety of no- and low-calorie beverages, providing easy access to calorie information and promoting physical activity."

"Sugar-Sweetened Beverages and Risk of Metabolic Syndrome and Type 2 Diabetes," Vasanti S. Malik, Barry M. Popkin, George A. Bray, Jean-Pierre Despres, Walter C. Willett, Frank B. Hu, Diabetes Care, vol. 33, no. 11, online Oct. 27, 2010.