Hiroshi OSAWA A Study of Nutrition and Behavior With Particular Reference to Functional Hypoglycemia In order to understand causes of various kinds of problem behavior in the present time, it is assumed that nutritional approach is necessary. One of the most important problems in the nutrition-behavior research is that of functional hypoglycemia. In our country, it is not known even by most of physicians. For diagnosis of functional hypoglycemia, 5-6 hour glucose tolerance test is needed. In this paper, five cases with results of 6-hour GTT are reported, and the importance of understanding of functional hypoglycemia is discussed.