Wolever Thomas M S, Brand-Miller Jennie C, Abernethy John, Astrup Arne, Atkinson Fiona, Axelsen Mette, Björck Inger, Brighenti Furio, Brown Rachel, Brynes Audrey, Casiraghi M Cristina, Cazaubiel Murielle, Dahlqvist Linda, Delport Elizabeth, Denyer Gareth S, Erba Daniela, Frost Gary, Granfeldt Yvonne, Hampton Shelagh, Hart Valerie A, Hätönen Katja A, Henry C Jeya, Hertzler Steve, Hull Sarah, Jerling Johann, Johnston Kelly L, Lightowler Helen, Mann Neil, Morgan Linda, Panlasigui Leonora N, Pelkman Christine, Perry Tracy, Pfeiffer Andreas F H, Pieters Marlien, Ramdath D Dan, Ramsingh Rayna T, Robert S Daniel, Robinson Carol, Sarkkinen Essi, Scazzina Francesca, Sison Dave Clark D, Sloth Birgitte, Staniforth Jane, Tapola Niina, Valsta Liisa M, Verkooijen Inge, Weickert Martin O, Weseler Antje R, Wilkie Paul, Zhang Jian
Department of Nutritional Sciences, University of Toronto and Glycemic Index Laboratories, Inc, Toronto, Ontario, Canada.
Am J Clin Nutr. 2008 Jan;87(1):247S-257S. doi: 10.1093/ajcn/87.1.247S.
Many laboratories offer glycemic index (GI) services.
We assessed the performance of the method used to measure GI.
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.
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).
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.
许多实验室提供血糖生成指数（GI）检测服务。
我们评估了用于测量GI的方法的性能。
采用粮农组织/世界卫生组织方法，在28个实验室（n = 311名受试者）中测量了奶酪泡芙和水果软糖（集中提供）的GI。各实验室报告其计算结果，并将原始数据集中发送进行重新计算。
54%的实验室报告的曲线下增量面积（AUC）值与集中计算结果不同。由于这一点以及数据分析中的其他差异，19%报告的食物GI值与集中计算值相差超过5个单位。个体受试者的GI值与年龄、性别、种族、体重指数或AUC无关，但与个体内变异（以重复参考食物测试的AUC的CV表示，即refCV）呈负相关（P = 0.033）。奶酪泡芙和水果软糖的实验室间GI值（平均值±标准差）分别为74.3±10.5和33.2±7.2。实验室平均GI与refCV（P = 0.003）以及测试前酒精摄入限制类型相关（P = 0.006，模型的r2 = 0.509）。实验室内部GI的标准差与refCV（P < 0.001）、葡萄糖分析方法（P = 0.010）、葡萄糖测量是否重复（P = 0.008）以及前一晚晚餐的限制情况相关（P = 0.013，模型的r2 = 0.810）。
GI值的实验室间标准差约为9。为保证准确性，需要标准化的数据分析以及低的受试者内变异（refCV < 30%）。结果表明，对于哪些因素需要控制以及哪些因素不需要控制以提高精度，存在常见的误解。需要进行对照研究和成本效益分析以优化GI方法。该试验已在clinicaltrials.gov上注册，注册号为NCT00260858。
