Holding that side of fries might help thwart type 2 diabetes, new research suggests.

In a long-term study of nearly 85,000 U.S. women, researchers at Harvard University found that those with the highest potato intake had a modestly elevated risk of developing type 2 diabetes.

The link was strongest among obese women, who are already at increased risk of the disease, suggesting that heavy potato consumption may pose a particular problem for them, the researchers point out.

The findings are published in the American Journal of Clinical Nutrition.

Though potatoes have healthful attributes, they also have a high glycemic index (GI) - meaning they cause a rapid, strong rise in blood sugar. Over time, these surges may damage the pancreatic cells that produce the hormone insulin, which is needed to metabolize blood sugar.

Overweight or sedentary adults may be particularly vulnerable to the effects of high-GI foods because they often have underlying insulin resistance - a precursor to diabetes in which body cells lose their sensitivity to insulin.

So it would make sense for these individuals to lay off the french fries, Thomas L. Halton, the lead author of the new study, told Reuters Health.

He and his colleagues found that women with the highest potato intake were 14 percent more likely than those with the lowest intake to develop diabetes over 20 years. And women who ate the most french fries, specifically, had a 21 percent greater risk of diabetes than those who ate the fewest.

Overall diet and other lifestyle habits did not explain the link, and potatoes seemed to be more problematic when a woman ate them instead of whole grains.

Whole grains - as well as many high-fiber vegetables, fruits and legumes - have a lower GI than potatoes and white-flour products. So eating those foods in place of potatoes, Halton’s team concludes, could potentially cut diabetes risk.

SOURCE: American Journal of Clinical Nutrition, February 2006.