Measuring the glycemic index of foods: interlaboratory study.
Journal article, 2008
BACKGROUND: Many laboratories offer glycemic index (GI) services. OBJECTIVE: We assessed the performance of the method used to measure GI. DESIGN: The GI of cheese-puffs and fruit-leather (centrally provided) was measured in 28 laboratories (n=311 subjects) by using the FAO/WHO method. The laboratories reported the results of their calculations and sent the raw data for recalculation centrally. RESULTS: Values for the incremental area under the curve (AUC) reported by 54% of the laboratories differed from central calculations. Because of this and other differences in data analysis, 19% of reported food GI values differed by >5 units from those calculated centrally. GI values in individual subjects were unrelated to age, sex, ethnicity, body mass index, or AUC but were negatively related to within-individual variation (P=0.033) expressed as the CV of the AUC for repeated reference food tests (refCV). The between-laboratory GI values (mean+/-SD) for cheese-puffs and fruit-leather were 74.3+/-10.5 and 33.2+/-7.2, respectively. The mean laboratory GI was related to refCV (P=0.003) and the type of restrictions on alcohol consumption before the test (P=0.006, r2=0.509 for model). The within-laboratory SD of GI was related to refCV (P<0.001), the glucose analysis method (P=0.010), whether glucose measures were duplicated (P=0.008), and restrictions on dinner the night before (P=0.013, r2=0.810 for model). CONCLUSIONS: The between-laboratory SD of the GI values is approximately 9. Standardized data analysis and low within-subject variation (refCV<30%) are required for accuracy. The results suggest that common misconceptions exist about which factors do and do not need to be controlled to improve precision. Controlled studies and cost-benefit analyses are needed to optimize GI methodology. The trial was registered at clinicaltrials.gov as NCT00260858.
Adolescent
Adult
classification
Sensitivity and Specificity
Reference Values
Humans
Blood Glucose
Laboratory Techniques and Procedures
Glycemic Index
Middle Aged
Female
Male
Glucose Tolerance Test
metabolism
Reproducibility of Results
standards
Food
Area Under Curve
Cross-Over Studies
Food Analysis
standards
metabolism
Dietary Carbohydrates
Aged
Author
Thomas M S Wolever
Jennie C Brand-Miller
John Abernethy
Arne Astrup
Fiona Atkinson
Mette Axelsen
University of Gothenburg
Inger Björck
Furio Brighenti
Rachel Brown
Audrey Brynes
M Cristina Casiraghi
Murielle Cazaubiel
Linda Dahlqvist
Elizabeth Delport
Gareth S Denyer
Daniela Erba
Gary Frost
Yvonne Granfeldt
Shelagh Hampton
Valerie A Hart
Katja A Hätönen
C Jeya Henry
Steve Hertzler
Sarah Hull
Johann Jerling
Kelly L Johnston
Helen Lightowler
Neil Mann
Linda Morgan
Leonora N Panlasigui
Christine Pelkman
Tracy Perry
Andreas F H Pfeiffer
Marlien Pieters
D Dan Ramdath
Rayna T Ramsingh
S Daniel Robert
Carol Robinson
Essi Sarkkinen
Francesca Scazzina
Dave Clark D Sison
Birgitte Sloth
Jane Staniforth
Niina Tapola
Liisa M Valsta
Inge Verkooijen
Martin O Weickert
Antje R Weseler
Paul Wilkie
Jian Zhang
American Journal of Clinical Nutrition
0002-9165 (ISSN) 19383207 (eISSN)
Vol. 87 1 247S-257SSubject Categories
Endocrinology and Diabetes
Clinical Medicine
MEDICAL AND HEALTH SCIENCES
Nutrition and Dietetics
PubMed
18175765