Background – Glycemic Response (GR) is the extent to which any food raises the blood glucose level and is controlled by the structure of the carbohydrate and its rate of digestion and absorption by the small intestine. Glycaemic index (GI) is a measure used to rank carbohydrates based on their effect on the blood glucose level relative to a standard such as pure glucose. One of the factors which may change the rate of gastrointestinal emptying, digestion and absorption and hence influence the GR and GI value is ethnicity.
Objective – To ascertain the effect of racial differences on glycaemic response and glycaemic index of white bread: comparing Western European vs. South East Asian cohorts.
Design – The standard Oral Glucose Tolerance Test (OGTT) was performed for both the standard food (glucose solution) and the test food (white bread) on 40 healthy individuals, age 18 to 45 years from Western European and South East Asian backgrounds. The “Homebrand” white bread was selected as the test food and was consumed on one occasion. A 50g glucose solution was used as the standard food and consumed on 3 occasions by the subjects. Finger prick blood samples in duplicates were obtained and instant blood glucose concentration was measured using automatic analyzers (HemoCue® glucose 201) over a two hour period. The area under the curve (AUC) for each 2h blood glucose response to the glucose solutions and the white bread was calculated and used to determine the GI value of the test food.
Outcomes – There were 55% females and 45% males in each ethnic group. The AUC for both the glucose standard (M = 234, SD = 8.1) and the test food (M = 174, SD = 13.4) were greater in Asian subjects compared with Caucasians (M = 214, SD = 12.6) and (M = 153, SD= 4.2). An ANOVA test showed no significant differences in the GI value of white bread F (2, 37) = 0.29, P =0.6 between Asian (M= 78, SEM= 5.4) and Caucasians (M= 73, SEM= 8.6).
Conclusion – The in vivo determination of the GI value of foods can not be influenced by ethnicity of the participants.