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Measuring the glycemic index of foods: interlaboratory study

Wolever, Thomas M. S.; Brand-Miller, Jennie C.; Abernethy, John; Astrup, Arne; Atkinson, Fiona; Axelsen, Mette; Björck, Inger LU ; Brighenti, Furio; Brown, Rachel and Brynes, Audrey, et al. (2008) In American Journal of Clinical Nutrition 87(1). p.247-257
Abstract
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,... (More)
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, r(2) = 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, r(2) = 0.810 for model). Conclusions: The between-laboratory SD of the GI values is approximate to 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. (Less)
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keywords
clinical trial, dietary carbohydrate, glycemic index, methodology, glucose, humans
in
American Journal of Clinical Nutrition
volume
87
issue
1
pages
247 - 257
publisher
American Society for Clinical Nutrition
external identifiers
  • wos:000252298500040
  • scopus:38149124794
ISSN
1938-3207
language
English
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yes
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d045c870-7185-43f2-8999-e089903ba1dc (old id 1200132)
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http://www.ajcn.org/cgi/content/full/87/1/247S
date added to LUP
2008-09-12 11:17:42
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2017-10-01 04:31:42
@article{d045c870-7185-43f2-8999-e089903ba1dc,
  abstract     = {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 &gt; 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, r(2) = 0.509 for model). The within-laboratory SD of GI was related to refCV (P &lt; 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, r(2) = 0.810 for model). Conclusions: The between-laboratory SD of the GI values is approximate to 9. Standardized data analysis and low within-subject variation (refCV &lt; 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.},
  author       = {Wolever, Thomas M. S. and Brand-Miller, Jennie C. and Abernethy, John and Astrup, Arne and Atkinson, Fiona and Axelsen, Mette and Björck, Inger and Brighenti, Furio and Brown, Rachel and Brynes, Audrey and Casiraghi, M. Cristina and Cazaubiel, Murielle and Dahlqvist, Linda and Delport, Elizabeth and Denyer, Gareth S. and Erba, Daniela and Frost, Gary and Granfeldt, Yvonne and Hampton, Shelagh and Hart, Valerie A. and Hatonen, Katja A. and Henry, C. Jeya and Hertzler, Steve and Hull, Sarah and Jerling, Johann and Johnston, Kelly L. and Lightowler, Helen and Mann, Neil and Morgan, Linda and Panlasigui, Leonora N. and Pelkman, Christine and Perry, Tracy and Pfeiffer, Andreas F. H. and Pieters, Marlien and Ramdath, D. Dan and Ramsingh, Rayna T. and Robert, S. Daniel and Robinson, Carol and Sarkkinen, Essi and Scazzina, Francesca and Sison, Dave Clark D. and Sloth, Birgitte and Staniforth, Jane and Tapola, Niina and Valsta, Liisa M. and Verkooijen, Inge and Weickert, Martin O. and Weseler, Antje R. and Wilkie, Paul and Zhang, Jian},
  issn         = {1938-3207},
  keyword      = {clinical trial,dietary carbohydrate,glycemic index,methodology,glucose,humans},
  language     = {eng},
  number       = {1},
  pages        = {247--257},
  publisher    = {American Society for Clinical Nutrition},
  series       = {American Journal of Clinical Nutrition},
  title        = {Measuring the glycemic index of foods: interlaboratory study},
  volume       = {87},
  year         = {2008},
}