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

Am J Clin Nutr. 2009 Jan;89(1):97-105. doi: 10.3945/ajcn.2008.26354. Epub 2008 Dec 3.


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 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.

MeSH terms

  • Adult
  • Area Under Curve
  • Blood Glucose / metabolism*
  • Diabetes Mellitus, Type 2 / diet therapy*
  • Diabetes Mellitus, Type 2 / metabolism
  • Diet, Diabetic
  • Dietary Carbohydrates / classification
  • Dietary Carbohydrates / pharmacokinetics*
  • Dose-Response Relationship, Drug
  • Female
  • Food, Organic
  • Glycemic Index*
  • Humans
  • Hyperglycemia
  • Intestinal Absorption / drug effects*
  • Male
  • Postprandial Period
  • Statistics, Nonparametric


  • Blood Glucose
  • Dietary Carbohydrates