People with type 2 diabetes are frequently told to avoid eating potatoes, and other high Glycemic Index (GI) foods, because of the longstanding perception that these foods make it difficult to control blood sugar levels.
This is especially problematic during the night when blood sugar tends to spike — a phenomenon that has been associated with cardiovascular disease and endothelial dysfunction.
But in a new study, researchers found that GI is not an accurate surrogate for a person’s glycemic response (GR) to food consumed as part of an evening meal.
They found that people actually had a better ‘nocturnal’ GR when they ate a mixed meal with skinless white potatoes compared to a macronutrient-matched mixed meal that included a low GI carbohydrate food — basmati rice.
The research was conducted by a team at Australian Catholic University in Melbourne.
In the study, people were provided the same breakfast and lunch, but they were randomly assigned to one of four dinners, each including either skinless white potatoes (test meal) prepared in three different ways (boiled, roasted, boiled then cooled then reheated) or basmati rice (control meal).
In addition to having blood samples collected regularly (both immediately after the meal and again every 30 minutes, for 2 hours), participants also wore a continuous glucose monitor overnight to track changes in blood sugar levels while sleeping.
The team found there were no differences between meals in glucose response following the dinner that contained any of the potato dishes or basmati rice.
Moreover, participants’ overnight GR was more favorable after eating the evening meal that included any of the high GI potato side dishes compared to low GI basmati rice.
These findings are contrary to that of observational research and traditional dietary guidance that has led some to believe potatoes are not an appropriate food choice for people with type 2 diabetes.
The study shows high GI foods, like potatoes, can be consumed as part of a healthy evening meal without negatively affecting GR — and while delivering key nutrients in relatively few calories, which is essential for people with type 2 diabetes.
The researchers conclude that potatoes are a vegetable that is sustainable, affordable, and nutrient-dense, and thus, they can play an important role in modern diets irrespective of metabolic health status.
One author of the study is Dr. Brooke Devlin, PhD.
The study is published in Clinical Nutrition.
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