In older children and adults, moderately severe hypoglycemia can resemble mania, mental illness, drug intoxication, or drunkenness.
Cases of death or permanent neurological damage occurring with a single episode have usually involved prolonged, untreated unconsciousness, interference with breathing, severe concurrent disease, or some other type of vulnerability.
Adjustment of efficiency of transfer of glucose from blood across the blood–brain barrier into the central nervous system represents a third form of compensation which occurs more gradually.
Chronic hypoglycemia or hyperglycemia seems to result in an increase or decrease in efficiency of transfer to maintain CNS levels of glucose within an optimal range.
In insulin-dependent diabetic patients this phenomenon is termed hypoglycemia unawareness and is a significant clinical problem when improved glycemic control is attempted.