Abstract 16937: Glycemic Response to a Single Food is Influenced by Plasma HgbA1c Concentrations
The utility of glycemic index (GI) values for chronic disease risk management remains controversial. While absolute GI value determinations for individual foods have been shown to vary significantly in individuals with type 1 or type 2 diabetes, there is a dearth of data on the reliability of GI value determinations and potential sources of variability among healthy adults. Our objective was to determine the intra-individual (within an individual) and inter-individual (among individuals) variability in glycemic response to a single food challenge as well as biological factors that potentially mediate this response. GI value for white bread relative to glucose was determined in 63 volunteers free from chronic disease with fasting glucose values <125mg/dL and recruited to differ by sex, age (18 to 85 y) and BMI (19 to 35 kg/m2). Volunteers underwent 3 sets of food challenges. Each set involved glucose (500mL glucose solution, [100g/L]) and white bread + 500mL water (96 gm bread; equivalent to 50gm carbohydrate). Changes in blood glucose were monitored (arterialized venous blood sampling at 0, 15, 30, 45, 60, 90 and 120 minutes) and GI values were calculated using the incremental AUC method. Body composition was measured by dual-energy X-ray absorptiometry. Percent total fat (TF), lean muscle mass (LM) and lean plus bone mineral content (LM+BMC) was calculated for whole body, trunk and abdominal regions. The mean (± SD) GI value for white bread was 62 ± 15. The average intra-individual coefficient of variation (CV) was 45% and inter-individual CV was 25%. No significant association was observed between GI value for white bread and age, sex or body composition variables (BMI, waist circumference, waist:hip ratio, TF, LM or LM+BMC). In mixed models, baseline HgbA1c explained 15% of the inter-individual variability. The mean GI for white bread was significantly lower in individuals with HgbA1c values > 5.7 (57 ± 11 vs. 66 ± 15, p=0.03). These data indicate substantial variability in individual responses to GI value determinations, suggesting that it is unlikely to be good approach to guide food choices in the clinical setting. Additionally, glycemic control, even in healthy individuals, significantly contributes to the variability in glycemic response among individuals.
Author Disclosures: N.R. Matthan: None. L.M. Ausman: None. H. Tighiouart: None. E.J. Reverri: None. A.H. Lichtenstein: None.
- © 2014 by American Heart Association, Inc.