"One of the studies included in our analysis found that when adjusting for BMI, the association decreased by about half, suggesting that the association between [sugary drinks] and diabetes is partly mediated by body weight, but there is an independent association as well," she added.
The researchers also cautioned that higher levels of sugar-sweetened beverage intake could be a marker of an overall unhealthy diet. Those who drink too many sodas may also eat too much saturated or trans fat and not enough fiber, they said.
They concluded that the data "provide empirical evidence that intake of sugar-sweetened beverages should be limited to reduce obesity-related risk of chronic metabolic diseases."
Cantley added that the results could be stratified better, to look at patients who are "ultra-high" consumers of sugary drinks -- downing six to eight cans of Coke a day, for example.
"How much higher would the risk be if we took the really high consumers and focused on them?" he said. "The population [in this study] is diluted out by people drinking one or two beverages a day, which could underestimate how bad it might be."