Using a scale from 0 to 100 where glucose = 100 and white sugar is often measured to be 68-70. The GI of a given food is the relative extent to which the carbohydrates in that food (gram for gram) raise blood glucose levels compared to an equivalent amount of pure glucose. A low GI food is one that has an index of 55 or below, compared to glucose. In order to measure a food's GI value, it is necessary to feed the food to a group of healthy people and then collect blood samples from them at regular intervals over 2 hours while they digest the food. The concentration of glucose (sugar) in the blood samples is measured