I am disappointed with the American Diabetes Association’s Position statement: Evidence-Based Nutrition Principles and Recommendations for the Treatment and Prevention of Diabetes and Related Complications (1) and technical review of the same title (2). The recommendations are not based on evidence. There is no explanation of the methods used for searching the literature and selecting papers for inclusion, nor any indication of the criteria used to grade the evidence (3). The sections in the technical review dealing with carbohydrate contain several errors, but space does not allow me to deal with all of the issues. I will focus just on the following recommendation: “With regard to the glycemic effects of carbohydrates, the total amount of carbohydrate in meals or snacks is more important than the source or type.”
The technical review indicates that dietary carbohydrates consist of monosaccharides, disaccharides, polyols, oligosaccarides, polysaccharides, and fiber, and it includes discussion about using correct terminology when referring to dietary carbohydrate. Presumably, therefore, the authors understood the meaning of the term “carbohydrate,” and used it intentionally. There are no qualifications. Thus, it can be presumed that amount is always more important that source or type of carbohydrate without exception. This carries a great deal of weight because it is said to be based on A-level evidence, the highest possible level of evidence and supposedly virtually indisputable.
I will not dwell on the fact that this is not based on any evidence. No data comparing the relative effects of different amounts versus different sources of carbohydrate was considered, and a large amount of evidence against it was ignored. I want to point out that nonglycemic carbohydrates will not raise blood glucose, no matter how much is consumed. Thus, sometimes, source is more important than amount. By denying this, the recommendation may harm people with diabetes.
More and more carbohydrates with little or no effect on blood glucose, such as polyols, fructo-oligosaccharides, and resistant starch, are appearing in the food supply. Some foods contain most of their carbohydrate in this form. For example, chocolate bars containing over 90% of their carbohydrate as lactitol have been promoted at the annual meeting of the Canadian Diabetes Association for several years. Lactitol is not absorbed (4,5) and, therefore, presumably has no effect on blood glucose. If a person with type 1 diabetes based preprandial insulin dose primarily on the amount of carbohydrate, as recommended, too much insulin might be taken before consuming a snack or meal containing predominantly nonglycemic carbohydrates, and an unexpected hypoglycemic episode might result.
Perhaps I am over-reacting, but I would like to know why the authors made this recommendation and who will be responsible if someone is injured because of it?
Address correspondence and reprint requests to Thomas Wolever, Department of Nutritional Sciences, University of Toronto, Toronto, Ontario M5S 3E2, Canada. E-mail: firstname.lastname@example.org.
T.W. is the president and part owner of and has received consulting fees, donations, and grants from Glycaemic Index Testing Incorporated.