Unfortunately, when people have what is called REACTIVE
HYPOGLYCEMIA (when the body reacts by over-producing insulin, which
causes hypoglycemia), it can be difficult to show in a test. I have known people with classic symptoms who surely suffer from this problem who have had negative results from glucose tolerance tests. This is because there are so many factors that can contribute to hypoglycemia -- stress, hormones, activity, what foods you eat, and a myriad more.