it depends in which context this question is asked. There are some diets out there for weight loss which use glycemic index as a recommendation for which foods to eat. For an evaluation of such a diet, I usually refer to a good internet source like this one: http://www.mayoclinic.com/health/glycemic-index-diet/MY00770
If the question comes in the context of diabetes treatment, I refer to the medical health care provider.
Hope this helps.