Glycemic responses of patients with type 2 diabetes to individual carbohydrate-rich foods and mixed meals.

AIMS: Our purpose was to determine whether the glycemic index (GI) of individual foods applies to mixed meals. METHODS: The glycemic responses elicited by portions of 4 individual foods with 25 g of available carbohydrate when served alone (rice, lacy pancake, flatbread and noodles) and when made into typical Malaysian mixed meals (coconut milk rice, lacy pancake with chicken curry, flatbread with dhal curry and fried noodles) were measured in 10 subjects with type 2 diabetes. To allow calculation of the GI of the foods and the relative glycemic responses of the mixed meals, each subject also tested 25 g of glucose 3 times. Capillary blood glucose was measured at 30-min intervals for 180 min after consuming each test meal. RESULTS: The mean ± SEM incremental area under the curve (AUC) after flatbread (345 ± 26 mmol × min/l) was significantly greater than after rice (238 ± 35) and lacy pancake (235 ± 31, p < 0.05), with noodles being intermediate (294 ± 35). The AUC after the flatbread with dhal curry (341 ± 49), coconut milk rice (238 ± 39) and fried noodle (272 ± 42) mixed meals were similar to those after the individual foods, but the AUC after the lacy pancake with chicken curry mixed meal (388 ± 52) was significantly greater than after the individual food item (p < 0.01). CONCLUSIONS: The results support the utility of the GI of individual foods such as rice, flatbread and noodles when applied to mixed meals. The reason for the higher response after the lacy pancake mixed meal compared to the individual food is not clear and may warrant further research.

Measuring the glycemic index of foods: interlaboratory study.

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.

Glycemic index of common Malaysian fruits.

The objective of the present study was to measure the glycemic index of durian, papaya, pineapple and water-melon grown in Malaysia. Ten (10) healthy volunteers (5 females, 5 males; body mass index 21.18+/-1.7 kg/m2) consumed 50 g of available carbohydrate portions of glucose (reference food) and four test foods (durian, papaya, pineapple and watermelon) in random order after an overnight fast. Glucose was tested on three separate occasions, and the test foods were each tested once. Postprandial plasma glucose was measured at intervals for two hours after intake of the test foods. Incremental areas under the curve were calculated, and the glycemic index was determined by expressing the area under the curve after the test foods as a percentage of the mean area under the curve after glucose. The results showed that the area under the curve after pineapple, 232+/-24 mmolxmin/L, was significantly greater than those after papaya, 147+/-14, watermelon, 139+/-8, and durian, 124+/-13 mmolxmin/L (p<0.05). Similarly, the glycemic index of pineapple, 82+/-4, was significantly greater than those of papaya, 58+/-6, watermelon, 55+/-3, and durian, 49+/-5 (p<0.05). The differences in area under the curve and glycemic index among papaya, watermelon and durian were not statistically significant. We conclude that pineapple has a high glycemic index, whereas papaya is intermediate and watermelon and durian are low glycemic index foods. The validity of these results depends on the accuracy of the data in the food tables upon which the portion sizes tested were based.