When it comes to type 2 diabetes, added fructose may actually be the main cause. Scientists have discovered that added sugars, particular those containing fructose, are a principal driver of diabetes and pre-diabetes.

About one in ten adults worldwide has type 2 diabetes. The number of individuals with this disease has actually more than doubled from 153 million in 1980 to 347 million in 2008. In the United States alone, 29 million adults have type 2 diabetes and another 86 million have pre-diabetes.

"At current levels, added-sugar consumption and added-fructose consumption in particular, are fueling a worsening epidemic of type 2 diabetes," said James J. DiNicolantonio, one of the researchers, in a news release. "Approximately 40 percent of U.S. adults already have some degree of insulin resistance with projects that nearly the same percentage will eventually develop frank diabetes."

In order to better understand how fructose and added sugars might impact the onset of diabetes, the researchers examined data from animal experiments and human studies. Data from recent trials suggested that replacing glucose-only starch with fructose-containing table sugar (sucrose) resulted in significant adverse metabolic effects. These adverse effects were broader with increasing baseline insulin resistance and more profound with greater proportions of added fructose in the diet.

In fact, the evidence seemed to indicate that added sugar, especially added fructose, is a serious and growing public health problem. While fructose is found naturally in some whole foods like fruits and vegetables, consuming these foods poses no problem for human health. However, processed foods laden with added sugars and fructose could pose risks.

"Most existing guidelines fall short of this mark at the potential cost of worsening rates of diabetes and related cardiovascular and other consequences," write the authors in a news release. "Limiting consumption of foods and beverages that contain added sugars, particularly added fructose, may be one of the single most effective strategies for ensuring one's robust future health."

The findings are published in the journal Mayo Clinic Proceedings.

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