Another approach to estimating the reliability of glycaemic index.
ABSTRACT The usefulness of the glycaemic index (GI) of a food for practical advice for individuals with diabetes or the general population depends on its reliability, as estimated by intra-class coefficient (ICC), a measure having values between 0 and 1, with values closer to 1 indicating better reliability. We aimed to estimate the ICC of the postprandial blood glucose response to glucose and white bread, instant mashed potato and chickpeas using the incremental area under the curve (iAUC) and the GI of these foods. The iAUC values were determined in twenty healthy individuals on three and four occasions for white bread and glucose, respectively, and for potato and chickpeas on a single occasion. The ICC of the iAUC for white bread and glucose were 0.50 (95 % CI 0.27, 0.73) and 0.49 (95 % CI 0.22, 0.75), respectively. The mean GI of white bread was 81 (95 % CI 74, 90) with a reliability of 0.27 indicating substantial within-person variability. The GI of mashed potato and chickpeas were 87 (95 % CI 76, 101) and 28 (95 % CI 22, 37) respectively with ICC of 0.02 and 0.40.The ICC of the iAUC were moderate and those of the GI fair or poor, indicating the heterogeneous nature of individuals' responses. The unpredictability of individual responses even if they are the result of day-to-day variation places limitations on the clinical usefulness of GI. If the very different GI of potato and chickpeas are estimates of an individual's every-day response to different foods, then the GI of foods may provide an indication of the GI of a long-term diet.
Full-textDOI: · Available from: Tim John Green, Feb 03, 2014
Article: A glance at… glycemic indexNutrition 03/2015; 31(3):539-41. DOI:10.1016/j.nut.2014.10.013 · 3.05 Impact Factor
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ABSTRACT: The degree to which an individual's glycemic response to a meal is determined by the glycemic index (GI) and other components of the meal remains unclear, especially when meals are not consumed in a highly controlled research setting. To address this question, we analyzed data collected during the run-in period of a clinical trial. Free-living, nondiabetic adults (n = 57) aged 53.9 ± 9.8 y (mean ± SD) with a BMI of 33.9 ± 5.3 kg/m(2) and waist circumference of 109 ± 11 cm underwent a 75-g oral glucose tolerance test (OGTT) and, on a separate day, wore a continuous glucose-monitoring system (CGMS) for 24 h during which time they recorded all foods consumed. The protein, fat, and available carbohydrate (avCHO) content and GI of the breakfast meals were calculated from the food records and the incremental areas under the glycemic response curves (iAUC) for 2 h after breakfast (iAUC(breakfast)) were calculated from CGMS data. Values for iAUC(breakfast), avCHO, fat, fiber, and BMI were normalized by log-transformation. The ability of participant characteristics and breakfast composition to predict individual iAUC(breakfast) responses was determined using step-wise multiple linear regression. A total of 56% of the variation in iAUC(breakfast) was explained by GI (30%; P < 0.001), iAUC after the OGTT (11%; P < 0.001), avCHO (11%; P < 0.001), and waist circumference (3%; P = 0.049); the effects of fat, protein, dietary fiber, age, sex, and BMI were not significant. We concluded that, in free-living, abdominally obese adults, GI is a significant determinant of individual glycemic responses elicited by self-selected breakfast meals. In this study, GI was a more important determinant of glycemic response than carbohydrate intake.Journal of Nutrition 11/2011; 142(1):27-32. DOI:10.3945/jn.111.146571 · 4.23 Impact Factor
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ABSTRACT: To compare postprandial glycaemic responses between Asian and Caucasian subjects. Postprandial capillary blood glucose concentrations were measured as 2-h incremental areas-under-the-curve (iAUCs) following consumption of a glucose beverage and a breakfast cereal in 27 Asians and 73 Caucasians. The mean difference in iAUC was 29%(95%CI 10, 51) and 63%(95%CI 32, 102) higher in the Asian compared with the Caucasian group following the glucose beverage and cereal, respectively.The glycaemic index (GI) of the cereal was 77(95%CI 66, 90) in the Asian group and 61 (95% CI 55, 67) in the Caucasian group; the values were different (P = 0.01). The findings suggest that dietary recommendations for people with diabetes and those at risk of Type 2 diabetes may be more appropriate if based on research in the ethnic group for which they are intended.Diabetic Medicine 10/2010; 27(10):1205-8. DOI:10.1111/j.1464-5491.2010.03069.x · 3.06 Impact Factor