Potatoes do not need to be off-limits if you have type 2 diabetes, ACU research

Whether baked, mashed, fried, boiled, or steamed, potatoes are one of the most popular foods in Aussie diets, but the humble spud is a carbohydrate-based food that people with type 2 diabetes are typically told to avoid for fear of spikes in blood sugar.

New research undertaken at ACU shows there is no reason for people with type 2 diabetes to bypass potatoes when they are eaten as part of a well-balanced evening meal.

Nutrition researchers at the Mary MacKillop Institute for Health Research found people with type 2 diabetes recorded lower overnight blood sugar levels after eating a potato-based evening meal when compared to those eating the same meal with rice.

Published in the journal Clinical Nutrition, the research compared the effect on overnight blood sugar levels of boiled, roasted, boiled and then cooled skinless white potatoes served with chicken and vegetables compared to the same meal served with rice.

People with type 2 diabetes frequently avoid eating potatoes, and other high glycaemic index (GI) foods, because of a longstanding perception that these foods make it difficult to control blood sugar levels. Research has linked high overnight blood sugar levels during sleep to cardiovascular disease.

“The advice for people with type 2 diabetes is to limit foods that have a high GI,” says lead author Brooke Devlin, who is now at La Trobe University.

“Our study shows people with type 2 diabetes should not avoid eating potatoes based solely on their GI rankings alone.

“High GI foods, like potatoes, can be consumed as part of a healthy evening meal without negatively affecting glucose release while delivering key nutrients in relatively few calories, which is essential for people with type 2diabetes.” 

Dr Devlin said GI of foods is still very relevant to people with type 2 diabetes in their blood glucose control and diabetes management, but excluding foods solely based on GI recommendations may lead to unnecessary avoidance of nutrient rich foods.

Despite a relatively low energy density, potatoes are classified as a high glycaemic index (GI) food. However, as Dr Devlin notes, “when testing for GI, foods are generally consumed in isolation typically following an overnight fast in ‘healthy’ individuals with normal glycaemic control.”

“There are limitations using the GI of single foods and their acute effect on blood glucose when trying to determine their influence on long-term health indices, particularly in people with type 2 diabetes as individual foods are rarely consumed in isolation but are more likely to be eaten with other foods as part of mixed meals,” she said.

“It’s rare that people eat foods in isolation, and findings from this study demonstrate how other factors, such as the time of day or food pairings, need to be considered when investigating the glucose release of mixed meals in individuals with type 2 diabetes.”

Dr Devlin said people with diabetes can eat potatoes in many forms, but it’s important to understand the effect they can have on blood sugar levels and the appropriate portion sizes.

This research was supported by funding from Alliance for Potato Research and Education (APRE).

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