Oct. 27, 2010 -- Drinking one or two sugar-sweetened beverages a day increases diabetes risk by 26%, a study shows.
In the new analysis, researchers pooled the findings of 11 previously published studies including more than 320,000 participants, attempting to assess the ''big picture."
"Drinking sugar-sweetened beverages is certainly and consistently associated with an increased risk of diabetes and metabolic syndrome," says researcher Vasanti Malik, ScD, a postdoctoral research fellow at the Harvard School of Public Health.
The researchers took into account sugar-sweetened soft drinks, fruit drinks, iced tea, and energy and vitamin water drinks. Beverages that are 100% fruit juice without added sweeteners were not counted as sugar-sweetened beverages in the research.
The Big Picture
By pooling the results of previously published studies, Malik says, the researchers hoped to provide an overall picture of how great the risk is and how consistent the evidence. "We pooled all these studies and came up with one overall measure of association," she tells WebMD.
Habitual drinkers -- those drinking one to two sugar-sweetened beverages a day on average -- had a 26% increased risk of developing type 2 diabetes and a 20% increased risk for developing metabolic syndrome compared to those who drank the beverages once a month or not at all, Malik says.
Eight of the studies looked at diabetes risk and three at metabolic syndrome risk. Participants in the diabetes studies totaled 310,819, with 15,043 cases of type 2 diabetes. In the metabolic syndrome studies, there were 19,431 participants and 5,803 cases of metabolic syndrome.
In the 11 studies, ages ranged from 21 to 84; the follow-up period ranged from four to 20 years.
Nearly 18 million people in the U.S. are diagnosed with diabetes, according to the American Diabetes Association; most have type 2 diabetes, in which the body doesn't make enough of the hormone insulin or doesn't use it effectively. Insulin takes sugar from the blood to the cells.
The risk of developing type 2 diabetes varies from person to person, depending on such factors as family history, ethnicity, weight, and age.
The link between sugar-sweetened beverages and diabetes and metabolic syndrome risk can be partially explained by the weight gain that can result from drinking the sugar-sweetened beverages, which in turn boosts type 2 diabetes risk, the researchers say. The sugar-sweetened drinks can also raise blood sugar and insulin concentrations quickly, in turn leading to insulin resistance and and higher risk of diabetes, according to the researchers.
The new analysis finds only correlations, not cause and effect, between sugar-sweetened beverages and diabetes, says Maureen Storey, PhD, senior vice president for science policy for the American Beverage Association, the trade association representing companies making non-alcoholic drinks.
In a statement, Storey says: "It is overly simplistic, and simply misleading, to suggest that reducing or eliminating sugar-sweetened beverages from the diet will uniquely lower [the] incidence of serious health conditions such as diabetes or metabolic syndrome."
A critical flaw in the studies analyzed, she says, is that "the authors focus only on the impact of one calorie source --- sugar-sweetened beverages -- on weight, rather than looking at all sources of calories."
A primary risk factor for both diabetes and metabolic syndrome, she says, is obesity, and maintaining a healthy weight can help reduce that risk. "And we know that the key to maintaining a healthy weight is balancing calories consumed, regardless of their source, with calories burned."
There's nothing unique, she says, about calories from sugar-sweetened beverages.
The new analysis "confirms what's known" about sugar-sweetened beverages and diabetes risk, says Stephanie Dunbar, RD, MPH, director of clinical affairs for the American Diabetes Association.
"This [new analysis] doesn't give us cause and effect, but I think it solidifies, 'Yes, we think there is an association there."
Limiting your intake of sugar-sweetened beverages is suggested by Malik and Dunbar. Try sparkling water with a lime wedge as an alternative, Malik says.
"For the general public, there's certainly no benefit from drinking these sugar-sweetened beverages," she says. "Everyone should be discouraged from drinking sugar-sweetened beverages, not just for the risk of diabetes and metabolic syndrome." She cites other research linking sugar-sweetened beverages to tooth decay and heart disease, among other ills.
Sugar-free diet beverages aren't an alternative she would endorse either. "Sure, artificially sweetened beverages are calorie-free for the most part, which is a good thing," she says, "but there are a lot of chemicals in them."
The intense sweet flavor in the artificially sweetened drinks, she says, may condition you to prefer more sweets in the diet.
Dunbar agrees: ''Even if you don't have diabetes, sugar-sweetened beverages are really not healthful."
But habits are hard to break, she tells WebMD. "For people drinking a lot of soda, they are probably not going to switch and drink just water." She suggests a gradual weaning from the sugary drinks. "You can use fruit juice and mix with seltzer or carbonated water. Work it down so you have just a little flavoring in the water."
And when you have to have a sugar-sweetened beverage? "Get the smallest size available," Dunbar says.