A study published in the American Journal of Clinical Nutrition found that assessing a meal using the glycemic index—which ranks the quality of carbohydrates in common foods—is an effective way to forecast the impact a meal has on blood sugar levels. This information is especially valuable for people with diabetes.
Dr. Thomas M. S. Wolever from the University of Toronto and his colleagues investigated whether the overall carbohydrate content and glycemic index of individual foods, as listed in published tables, could predict blood sugar responses to realistic mixed meals in healthy subjects.
The researchers evaluated six meals with 16 participants in Sydney and eight meals with 10 participants in Toronto, then pooled the data. These meals varied in calories, protein, fat, available carbohydrates, and glycemic index scores.
Blood sugar and insulin responses to the Sydney meals varied over a threefold range, while responses to the Toronto meals varied over a 2.4-fold range.
They found no correlation between blood sugar levels and the fat or protein content of the meals. However, there was a strong correlation with carbohydrate content and glycemic index, which together explained 88% of the variation in blood sugar response.
These findings confirm that the glycemic index is a useful tool for managing blood sugar. People with diabetes can benefit from glycemic index-based diets but should do so under medical supervision and continue prescribed therapies.
