The glycemic index (GI) is a method by which the glycemic impact of various foods is measured. The index measures foods based on a scale of 0-100, where a higher number indicates a food that releases its glucose quickly. Low GI foods are typically classified as having a GI range of under 55. These foods release their glucose at a slower rate, making them well-suited to individuals with diabetes or specific diets. Some common low GI foods include fruits, vegetables, meats and whole grains.
In order to determine the glycemic index of any particular food, a number of tests are performed. These tests are typically designed to measure how an individual's blood sugar reacts to eating the food. Foods with a high GI will tend to cause the blood sugar to spike, while low GI foods may cause blood glucose to increase more slowly. The glycemic index may use white bread or pure glucose to represent the highest possible number of 100. The particular GI number of any given food may differ depending on what was used as the control, though its relative position should not change.
Many people with diabetes are able to at least partially manage their conditions with low GI foods. People with diabetes typically lack the necessary insulin to deal with blood glucose, and low GI foods may help them keep their blood glucose at manageable levels. Some people with pre-diabetes may also avoid developing the full-blown disease by moderating their diets with low GI foods.
Several diets have been developed that utilize the glycemic index. Some of these diets may be used by people with diabetes under a doctor's supervision, though they are often used by people who are simply trying to lose weight. These diets typically use the glycemic index to indicate what can be eaten and in what amounts, with a preference given to foods that are lower on the glycemic index.
Many whole foods such as fruits, nuts and vegetables have low glycemic indexes. Whole grains also have a much lower glycemic index than refined grains, and while basmati rice isn't typically considered a low GI food, it does have a lower glycemic index than white rice. Other foods with a low GI include protein sources such as legumes, meats, eggs and milk. Fructose also has a very low glycemic index, though it may be more desirable in its natural state rather than as a food additive.