A potato (couch or not) in the diet adverse for diabetics.

'Potato-potato' burning bright in the hands of you could predispose you to an elevated risk of type 2 diabetes. According to a long-term study of nearly 85 000 United States women Harvard University researchers' found that those with the highest potato intake had a modestly elevated risk of developing type 2 diabetes.

Obese women, who are already at increased risk of the disease, had the strongest link which suggests that heavy potato consumption may pose a particular problem for them. American Journal of Clinical Nutrition has the research published.

Potatoes 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 metabolise 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.

Thomas L Halton, the lead author of the new study found women with the highest potato intake were 14% more likely than those with the lowest intake to develop diabetes over 20 years.

Whole grains - as well as many high-fiber vegetables, fruits and legumes - have a lower GI than potatoes and white-flour products. Therefore the diet should have more of these than potatoes.