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likely responses in people with diabetes. Most studies report that ingestion of a chocolate bar causes a substantially lower rise in plasma glucose and insulin than equivalent amounts of other carbohydrates (2022). Shively et al. (9) conducted one of the most comprehensive studies in normal subjects of glucose and insulin responses to various snack foods, including chocolate, potato chips, granola bars and peanut butter cups. They found that plasma glucose responses to the snacks, on both an isocaloric or equivalent carbohydrate basis, were uniformly lower than that after a glucose load. In contrast, insulin responses to the snacks exhibited more variability, the milk chocolate bar giving higher responses than those predicted by the level of glycemia. In fact, the insulin response to the chocolate bar was as high as that seen after the glucose load. There was no evidence, however, of rebound hypoglycemia.

Recently blood glucose and insulin responses were determined after consumption of 10 different chocolate products in 12 healthy volunteers with normal glucose tolerance (23). Their ages ranged from 2139 years (mean ± SD, 31 ± 6) and their body mass index (BMI) from 19 to 24 (22 ± 2) kg/m2. The subjects took 50 g available carbohydrate (starch + sugars) portions of each test food in random order on separate mornings after a 10-hour overnight fast. The nutrient composition and weight of the 50 g carbohydrate portion of the foods is shown in Table 12.2. The reference food (white bread) was tested twice during the study. Foods were consumed over 12 min with sufficient water to bring the total meal volume to 600 ml. Finger-prick capillary blood samples were taken at 0 (fasting), 15, 30, 45, 60, 90 and 120 min after the meal began. Blood glucose was assayed using the glucose hexokinase method and plasma insulin concentration was determined by radioimmunoassay using commercial kits.

To determine the GI of the foods according to standard methodology (24), the area under the incremental plasma glucose curve (AUC) was calculated geometrically using Simpson's rule, with the fasting value as the baseline. The AUC for the test food was then expressed as a percentage of the AUC for the reference food (the average AUC for the two bread tests) for that individual (= GI in that individual). GI values were multiplied by 0.7 so that a scale on which the glucose = 100 could be used to express the final results. The mean (± SE) Gl of each food was calculated as the average GI of all 12 individuals. The insulin index (II) was calculated in an analogous manner using the area under the plasma insulin curve. In instances where an individual gave a GI or II outside two standard deviations from the mean of the group, the result was excluded from further analysis.

The Glycemic Index of Chocolate Products

The GI and II of the foods tested are shown in Table 12.3. Figures 12.1 and 12.2 illustrate the glucose and insulin responses to the chocolate bar.

The findings indicate that most of the chocolate products produced relatively

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