Glycemic Index

How quickly do foods raise your blood sugar?

The glycemic response of a food is a measure of the food's ability to elevate blood sugar. The glycemic response is influenced by the amount of food you eat, its fiber content, fat content or amount of added fat, and the way the food is prepared.

Highly glycemic carbohydrates are best consumed during and after exercise. They enter the bloodstream quickly and are readily available for fueling exercising muscles.

Low glycemic carbohydrates enter the bloodstream slowly and are best eaten before exercise. They provide sustained longer-term energy, and help maintain stable blood sugar levels during extended exercise periods (greater than one hour).

The glycemic index is a useful tool that measures how fast a particular food is likely to raise your blood sugar. It can be very helpful in managing your blood sugars. For example, if your blood sugar is low or it is dropping during exercise, you would prefer to eat carbohydrates that raise your blood sugar quickly. On the other hand, if you want to keep your blood sugar from dropping during a few hours of mild activity, you might prefer to eat extra carbohydrate with a lower glycemic index and longer action time. And if your blood sugar tends to spike after breakfast, you would want to select a cold cereal with a lower glycemic index. 

The numbers below are based on glucose, which is the fastest carbohydrate available except for maltose. Glucose is given a value of 100---other carbs are given a number relative to glucose. Faster carbs (higher numbers) are great for raising low blood sugars and for covering brief periods of intense exercise. Slower carbs (lower numbers) are helpful for preventing overnight drops in the blood sugar and for long periods of exercise. ( Note: if you prefer to use white bread as your standard, simply multiply the numbers below by 1.42, i.e., glucose would have a glycemic index of 142.)

Note that these numbers are compiled from a wide range of research labs, and as often as possible from more than one study. These numbers will be close but may not be identical to other glycemic index lists. The impact a food will have on blood sugars depends on many other factors like ripeness, cooking time, fiber and fat content, time of day, blood insulin levels, and recent activity. Use the Glycemic Index as just one of the many tools you have available to improve your control.