It is the glycaemic response to, not the carbohydrate content of food that matters in diabetes and obesity: The glycaemic index revisited

Abstract

IntroductionThere is currently substantial debate about the merits of an imminent United Kingdom (UK) tax on sugar-sweetened beverages and snacks that are high in sugar. 1 The most recent Scientific Advisory Committee report 2 advises a reduction of dietary sugar consumption in the UK; however, because of the furore surrounding sugar, the role of starchy carbohydrates as a source of blood sugar (glucose) has become understated, and the important role of the glycaemic index (GI) has become somewhat eclipsed. This article explains the GI as a predictor of the effect of food choices on blood glucose. We question whether higher GI carbohydrates (refined or unrefined) should also be viewed with caution in the diet and ask, for the purpose of communication with patients: can starch be viewed as a concentrated sugar?While working in the area of dietary choices for patients with obesity and type 2 diabetes (T2D) in a primary care setting, 3 we observed that many health professionals and patients when considering dietary choices were confused by the relative merits of using carbohydrate content of food in grams versus the foods' GI. Among the professionals, many erroneously assumed table sugar to affect blood glucose far more than the carbohydrate in a baked potato, for example, and others wrongly assumed that carbohydrate in different foods had a similar effect on blood glucose.GI and glycaemic load (GL) values have been tabulated for the various carbohydrate foods. 4 The position of any food in a GI or GL league table is determined by the food's effect on post-prandial blood glucose. This is determined by both the type and the amount of carbohydrates in the food and also how quickly the food can be digested. For compliance with guidelines on healthy eating, separate league tables for each food group in the guidelines can be advised. The effect of foods on Background: The low-carbohydrate diet for diabetes and obesity is over 200 years old. A new lease of life comes with evidence for its beneficial effects supplied by research into the value of low-glycaemic index (GI) foods in diabetes control. While trialling this approach it became evident that professionals and patients had previously misunderstood the index leading to errors in food choices.

Dietary Glycemic Index and Load and the Risk of Type 2 Diabetes: Assessment of Causal Relations

“…Meta-analysis has shown a sufficient reduction in dietary GI or GL does result in a dose-dependent reduction in body weight in free-living persons with diabetes without them attempting to control their food intake [37]. Reduced glycemic load by avoidance of high GI carbohydrate foods has also resulted in the loss of body weight and gaining control of T2D [85,86,87]. Lower GI diets have also helped body weight reduction and maintenance, particularly with a background diet high in protein [88,89,90].…”

Dietary Glycemic Index and Load and the Risk of Type 2 Diabetes: A Systematic Review and Updated Meta-Analyses of Prospective Cohort Studies

“…In comparing the relative strengths of the T2D–GI and GL relations, it should be recognized, however, that it is not a question of which is better. GI and GL may find preference according to the situation of the person or patient [79,80].…”

Coronary Heart Disease and Dietary Carbohydrate, Glycemic Index, and Glycemic Load: Dose-Response Meta-analyses of Prospective Cohort Studies

“…Meta-analysis has revealed that lower GL diets, achieved using lower GI carbohydrate foods, result in a dose-dependent reduction in body weight among persons with varied glycemic control from normal to the diabetic state 59 . Further, avoidance of high GI foods to achieve a lower GL diet has proved effective in improving body weight and glycemic and lipidemic parameters over a mean of 13 months in prediabetic and diabetic patients 69, 70. Beneficial effects of low GI and GL have become evident in long-term primary prevention of obesity-associated diseases 75 .…”