New study findings show that people with type 2 diabetes can better maintain overnight glycemic control when high Glycemic Index (GI) potatoes are included in an evening meal versus low GI basmati rice.
People with type 2 Diabetes (T2D) 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.
However, for the first time, a rigorously controlled clinical trial, including 24 adults with T2D, demonstrates that GI is not an accurate surrogate for an individual's glycemic response (GR) to a food consumed as part of an evening meal. Specifically, the findings published in Clinical Nutrition show that participants had a better 'nocturnal' GR when they ate a mixed meal with skinless white potatoes compared to an isoenergetic and macro nutrient-matched mixed meal that included a low GI carbohydrate food- basmati rice.
"Despite its frequent use among nutrition researchers, GI is not an appropriate tool for understanding how a meal impacts glycemic control; it is a very specific measurement for foods consumed in isolation, typically conducted under controlled laboratory conditions," says Dr. Brooke Devlin, PhD, the primary investigator, at Australian Catholic University in Melbourne. "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 GR of mixed meals in individuals with T2D."
Participants 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). Participants repeated the experiment, with a 9-day break in between each trial, to cycle through all test meals and the control. In addition to having blood samples collected regularly, participants also wore a continuous glucose monitor overnight to track changes in blood sugar levels while sleeping.
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.
