(01-02-09) Glycemic index, postprandial glycemia, and the shape of the curve in healthy subjects:

analysis of a database of more than 1000 foods1,2


Jennie C Brand-Miller, Karola Stockmann, Fiona Atkinson, Peter Petocz and Gareth Denyer

1 From the Institute of Obesity, Nutrition and Exercise (JCB-M), and the School of Molecular and Microbial Biosciences (JCB-M, KS, FA, and GD), The University of Sydney, Sydney, Australia, and the Department of Statistics, Macquarie University, Sydney, Australia (PP).
2 Reprints not available. Address correspondence to JC Brand-Miller, Human Nutrition Unit, G08, The University of Sydney, Sydney, NSW, 2006. E-mail: [email protected] .
Background: The glycemic index (GI) characterizes foods by using the incremental area under the glycemic response curve relative to a similar amount of oral glucose. Its ability to differentiate between curves of different shapes, the peak response, and other aspects of the glycemic response is debatable.
Objective: The objective was to explore the association between a food's GI and the shape of the curve in healthy individuals.
Design: A large database of 1126 foods tested by standardized GI methodology in 8?12 healthy subjects was analyzed systematically. Each food's absolute and incremental blood glucose concentrations were compared at individual time points with the GI. The average curve was generated for low-GI ( 55), medium-GI (56?69), and high-GI ( 70) foods within major food categories.
Results: The GI of individual foods was found to correlate strongly with the incremental and actual peak (Spearman's correlations of r = 0.76 and r = 0.73, respectively), incremental and actual glucose concentration at 60 min (r = 0.70 and r = 0.66, respectively), and maximum amplitude of glucose excursion (r = 0.68) (all P < 0.001). In contrast, there was only a weak correlation between the food's GI and the 120-min glucose concentration (incremental r = 0.20, P < 0.001; absolute r = 0.16, P < 0.001). Within food groups, the mean GI, 30- and 60-min glucose concentrations, and maximum amplitude of glucose excursion varied significantly for foods classified as having a low, medium, or high GI (P < 0.001).

Source: Am J Clin Nutr 89: 97-105, 2009.

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