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Blood Glucose Levels

How glycemic indexes are determined

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How are glycemic indexes determined?

In order to determine the value of Glycemic Indexes of food, experimental procedures must be conducted.
1. A test volunteer is fed a portion of a food that contains exactly fifty grams of net carbohydrates
(Net carbohydrates are the total amount of carbohydrate in a particular food minus the total fiber)
2. Test volunteers must have an overnight fast for the results to be accurate.
3. Individual's blood glucose levels are measured initially.
4. The food must be eaten within in fifteen minutes.
5. The blood glucose levels of the participant are recorded every fifteen minutes for the next two to three hours.
6. To then determine the Glycemic Index of the food, it is compared to the glycemic response of the volunteer to fifty grams of pure glucose. The ratio that is determined from the comparison of the food to the pure glucose then determines the glycemic index (Caballero).

Glucose is given the value of 100 because all foods are compared to its value.


The increase in blood glucose levels in response to glucose (figure 1) and barley (figure 2).

Leslie Selcke
University of Illinois
FSHN 120 Honors Project
Fall 2005