Based on how fast a particular food raises blood sugar over a 2 - 3 hour period, the glycemic index uses a numbering index, whereby glucose is the reference point of 100. A baked potato for instance ranks 85 on that scale, brown rice 59, white bread 72, table sugar 65, bananas 51, milk 30, grapefruit 25, and broccoli 6. However, when comparing the databases of different researchers, one can find fast discrepancies with their rankings of certain foods, which doesn't help to support the validity of that system... Full Text