Estimating the reliability of glycemic index values and potential sources of methodological and biological variability

Abstract

Background: The utility of glycemic index (GI) values for chronic disease risk management remains controversial. Although absolute GI value determinations for individual foods have been shown to vary significantly in individuals with diabetes, there is a dearth of data on the reliability of GI value determinations and potential sources of variability among healthy adults. Objective: We examined the intra-and inter-individual variability in glycemic response to a single food challenge and methodologic and biological factors that potentially mediate this response. Design: The GI value for white bread was determined by using standardized methodology in 63 volunteers free from chronic disease and recruited to differ by sex, age (18-85 y), and body mass index [BMI (in kg/m 2 ): 20-35]. Volunteers randomly underwent 3 sets of food challenges involving glucose (reference) and white bread (test food), both providing 50 g available carbohydrates. Serum glucose and insulin were monitored for 5 h postingestion, and GI values were calculated by using different area under the curve (AUC) methods. Biochemical variables were measured by using standard assays and body composition by dual-energy X-ray absorptiometry. Results: The mean 6 SD GI value for white bread was 62 6 15 when calculated by using the recommended method. Mean intraand interindividual CVs were 20% and 25%, respectively. Increasing sample size, replication of reference and test foods, and length of blood sampling, as well as AUC calculation method, did not improve the CVs. Among the biological factors assessed, insulin index and glycated hemoglobin values explained 15% and 16% of the variability in mean GI value for white bread, respectively. Conclusions: These data indicate that there is substantial variability in individual responses to GI value determinations, demonstrating that it is unlikely to be a good approach to guiding food choices. Additionally, even in healthy individuals, glycemic status significantly contributes to the variability in GI value estimates. This trial was registered at clinicaltrials.gov as NCT01023646.Am J Clin Nutr 2016;104:1004-13.

Saturated Fatty Acids and Cardiovascular Disease: Replacements for Saturated Fat to Reduce Cardiovascular Risk

“…Matthan et al studied the glycemic response to a single food item in 63 healthy volunteers, and found substantial variability in their responses (20% within an individual and 25% between individuals) [86]. The authors suggest that the high degree of variability in glycemic response means that GI is unlikely to be a good method to inform food choices.…”

Rol De La Stevia Y L-Carnitina Sobre El Impacto Glicémico De Un Suplemento Nutricional en Adultos

“…Diversos estudios han informado que los alimentos con elevados valores de IG y CG se han relacionado con un mayor riesgo de diabetes (11,12), pero otros reportes no han confirmado estos resultados. Como estrategia para ayudar a mantener la euglicemia en el diabético, existen suplementos nutricionales específicos para diabetes utilizados como sustitutos calóricos nutritivos en individuos normopesos, con sobrepeso u obesos; o suplementos para desnutridos con diabetes mellitus tipo 2 (DM2) (13). La mayoría de estos productos diseñados con el fin de elongar la respuesta glicémica han sido edulcorados con distintos tipos de endulzantes.…”

Glycemic index is as reliable as macronutrients on food labels

“…In a recent article, Matthan et al (1) measured glucose and insulin responses elicited by 50-g available carbohydrate portions of white bread and glucose in 63 subjects. They concluded that the substantial variability in individual responses to glycemic index (GI) value determinations makes GI an unreliable approach to guiding food choices.…”

“…Matthan et al (1) reported that the mean 6 SD GI of Pepperidge Farm Original White Bread was 62.4 6 15.3, and they consider this amount of variation to be substantial enough to show that GI should not be used to guide food choices because of the potential to misclassify foods as low (GI 55), medium (56-69), or high (GI $70) GI. However, this interpretation is incorrect.…”