 The EEG signal reflects the functional state and metabolism of the brain. The brain is almost totally dependent on a continuous supply of glucose, and when this is lower than the metabolic requirements of the brain, its function deteriorates. Indeed, neuroglycopenic hypoglycemia in insulin-treated diabetic patients is associated with characteristic changes in EEG with a decrease in alpha activity, an increase in delta activity, and in particular an increase in theta activity 16-19. These changes are clearly seen at 2.0 mmoll 16,17, but may be present already at higher glucose levels 3.0 mmoll, in particular in type 1 diabetic patients with hypoglycemic unawareness 19,20. It has been shown that the most characteristic changes, the increase in theta activity, appears 19 min before severe cognitive impairment 20. This suggests a window between hypoglycemia-induced EEG changes and severe neuroglycepenia, which is an important prerequisite in developing an automatic detection system capable of warning the patient. 