Glycemic index, postprandial glycemia, and the shape of the curve in healthy subjects: analysis of a database of more than 1,000 foods.
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.


METHODS
A large database of 1,126 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 (< or = 55), medium-GI (56-69), and high-GI (> or = 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).


CONCLUSIONS
The GI provides a good summary of postprandial glycemia. It predicts the peak (or near peak) response, the maximum glucose fluctuation, and other attributes of the response curve.
Brand-Miller
Jennie C
JC
Institute of Obesity, Nutrition and Exercise, The University of Sydney, Sydney, NSW, Australia. j.brandmiller@mmb.usyd.edu.au
Stockmann
Karola
K
Atkinson
Fiona
F
Petocz
Peter
P
Denyer
Gareth
G
D000328:Adult; D019540:Area Under Curve; D001786:Blood Glucose / Q000378:metabolism*; D003924:Diabetes Mellitus, Type 2 / Q000178:diet therapy* / Q000378:metabolism; D003927:Diet, Diabetic; D004040:Dietary Carbohydrates / Q000145:classification / Q000493:pharmacokinetics*; D004305:Dose-Response Relationship, Drug; D005260:Female; D058870:Food, Organic; D038321:Glycemic Index; D006801:Humans; D006943:Hyperglycemia; D007408:Intestinal Absorption / Q000187:drug effects*; D008297:Male; D019518:Postprandial Period; D018709:Statistics, Nonparametric
D001786:Blood Glucose; D004040:Dietary Carbohydrates