Glycemic Index (GI) ranks an individual food on a scale of 1 to 100 based on how a standard 50-gram dose of that food causes blood glucose levels to rise within 2 hours when compared to white bread or glucose, which are given a glycemic index of 100. Low GI foods cause smaller rises in blood glucose levels and high GI foods cause higher rises.
Simple, huh? No one else thinks so, either. Glycemic Index may add some benefits to diabetes control, but it’s not a perfect system. Here’s why:
GI does not measure how quickly blood glucose levels increase, only how high they rise. Turns out that blood glucose levels tend to peak at about the same time, regardless of the food source.
GI of food varies according to degree of ripeness (a ripe banana has a higher GI than an under ripe banana), if it is cooked or raw (raw carrots have a lower GI than boiled carrots), and how it is processed (plain boiled macaroni has a lower GI than boxed macaroni and cheese).
GI varies if a food is eaten alone or with other foods. For example, white bread (high GI) eaten with peanut butter (low GI) produces a moderate GI response.
Individual foods affect blood glucose levels differently from day to day and person to person.
Glycemic Load (GL) is another method for predicting how foods will affect blood glucose levels. GL takes into account the amount of carbohydrate in a food as well as the glycemic index. For example, jam has a high GI, based on a 50-gram portion. But if you eat just 1 teaspoon (or 5 grams) of jam, the glycemic load is much less and produces a smaller rise in blood glucose levels.
Glycemic Index (GI) and Glycemic Load (GL) both attempt to measure Glycemic Response: How YOUR body responds to the foods YOU eat
Both GI and GL can help you fine-tune your diabetes control.
Don’t forget: Total carbohydrates still count in predicting how a meal or snack will affect your blood glucose levels.