Abstract 19680: Age but not Body Mass Index (BMI) or Sex Affect Glycemic Response to a Single Food in Healthy Subjects
Introduction: Few large-scale studies have evaluated the variability of glycemic index (GI) value determinations among individuals, particularly on the basis of biological parameters such as sex, age and body mass index (BMI). An understanding of these potential sources of variability is required to better define the utility of GI values for chronic disease risk assessment and management.
Hypothesis: Differences in age, sex and BMI affect glucose homeostasis and calculated GI values in response to a food challenge.
Design and Methods: The intra-individual reproducibility (within the same individual, when repeatedly measured) and inter-individual variability (among individuals) of GI value determinations for white bread relative to glucose, was evaluated in 56 volunteers recruited to differ by sex, age (18 to 85 y) and BMI (18.5 to 24.9, 25 to 29.9, 30 to 35 kg/m2). Each volunteer underwent 3 sets of food challenges in random order (6 sessions), after abstaining from strenuous physical activity and alcohol intake for at least 72 hours prior to each session. Each set involved ingestion of glucose (500mL glucose solution, [100g/L]) and white bread (96 gm Pepperidge Farm Original White Bread; 50 gm carbohydrate + 500mL water). Changes in blood glucose were monitored (arterialized venous blood sampling at 0, 15, 30, 45, 60, 90 and 120 mins) and GI values were calculated using the incremental AUC method over a 2-hour period.
Results: The mean (± SD) GI value for white bread was 63 ± 16. Intra-individual coefficient of variation (CV) ranged from 2 to 77% and the inter-individual CV was 25%. A significant association was observed between the GI value for white bread and age (r=0.30, p=0.028) but not for sex (63 ± 15 vs. 63 ± 18; males vs. females, p=0.96) or BMI (67 ± 18, 62 ± 14 and 58 ± 15 for BMI categories 18.5 to 24.9, 25 to 29.9 and 30 to 35, respectively, p=0.17).
Conclusion: These data indicate that the variability in GI values is explained, in part, by differences in age. The impact of this finding on estimates of associations between dietary GI and chronic disease risk assessment or management, especially with respect to CVD, needs to be considered.
- © 2010 by American Heart Association, Inc.