The glycemic index is a useful tool in the effective planning of meals to prevent “spikes” in the blood glucose level after meals.
Foods with a low glycemic index release glucose into the blood slowly and steadily, therefore ensuring the blood glucose level remains relatively constant. Preventing sharp increases in the blood glucose level is thought to help prevent several diseases such as coronary heart disease and type II diabetes.
However, there are limitations to bear in mind when calculating the glycemic index of foods and planning meals.
Some examples of these limitations are described below:
- The glycemic index only concerns the relative rise of blood sugar after a meal and not other bodily responses such as the insulin response. The insulin response to a meal can be measured using the insulin index.
- One of the major drawbacks of glycemic index is that the glycemic response to a particular food varies between individuals as well from day to day and even throughout different points in the day.
- The glycemic index of different types of foods can vary according to several factors. For example, the ripeness of a fruit may influence its glycemic index as can the variety of fruit and the preparation method used.
- Glycemic index is only based on the glycemic response two hours after a meal and not periods after that. In most diabetics, the blood sugar may be raised persistently for up to four hours after a meal.
Reviewed by Sally Robertson, BSc