The incidence studies on hypoglycemia in Type 1 Diabetes have revealed that the younger the child the more frequent and severe are the hypoglycemic episodes. The brain does not store glycogen and perform gluconeogenesis, it relies on a continuous supply of glucose from blood. There are several studies demonstrating the brain's ability to use lactate, alanine and ketone as alternative fuels yet there is no evidence showing that this mechanism works in diabetic individuals. During hypoglycemia, cerebral blood flow increases very little in children. It is unlikely that this mechanism alone explains the maintenance of glucose utilization. Up regulation of GLUT transporters may be an additional or alternative protective mechanism. Severe hypoglycemic episodes experienced particularly in early childhood can cause deterioration in neurocognitive functions. There are significant individual differences in terms of vulnerability to hypoglycemia. Adaptive responses to hypoglycemia might vary according to both the degree and frequency of prior hypoglycemia and the presence of structural brain changes induced by chronic hyperglycemia.