Meta-Analysis of Low-Glycemic Index Diets in the Management of Diabetes: Response to Franz

In her editorial (1) accompanying the meta-analysis carried out by Brand-Miller et al. (2), Dr. Franz describes the glycemic index as “not the most effective nutrition therapy intervention.” Her conclusion appears principally based on the fact that the reduction in HbA_1c by 0.4–0.6% units (a 7.4% decrease in glycated protein is equivalent to ∼0.6% HbA_1c units) when comparing high–and low–glycemic index diets is less than that seen when considering other dietary manipulations, which may achieve decreases in HbA_1c of 1–2% units (a 15–22% decrease in HbA_1c). Franz appears to have missed a pivotal issue clearly discussed by Brand-Miller et al. in their article (2). The observed improvement in glycemic control is the net improvement over and above that of standard current best practice nutrition therapy (and medication) in the institutions where the studies were conducted. By failing to acknowledge the additional benefit that may be achieved by the choice of low–glycemic index foods and emphasizing only the importance of total carbohydrate, the American Diabetes Association may be depriving people with diabetes of the full benefit of nutrition therapy. It is noteworthy that the recommendations of the Nutrition Study Group of the European Association for the Study of Diabetes (3) and the Food and Agriculture Organization/World Health Organization Expert Consultation on Carbohydrates (4) include advice to use the glycemic index as a means of determining the most appropriate choices of carbohydrate-containing foods.