Hypoglycemia or hypoglycaemia is the medical term for a state produced by a lower than normal level of blood glucose. The term literally means "under-sweet blood" (Gr. hypo-, glykys, haima).
Hypoglycemia can produce a variety of symptoms and effects but the principal problems arise from an inadequate supply of glucose as fuel to the brain, resulting in impairment of function (neuroglycopenia). Effects can range from vaguely "feeling bad" to seizures, unconsciousness, and (rarely) permanent brain damage or death.
The most common forms of moderate and severe hypoglycemia occur as a complication of treatment of diabetes mellitus with insulin or oral medications. Hypoglycemia is less common in non-diabetic persons, but can occur at any age, from many causes. Among the causes are excessive insulin produced in the body, inborn errors of carbohydrate, fat, amino acid or organic acid metabolism, medications and poisons, alcohol, hormone deficiencies, certain tumors, prolonged starvation, and alterations of metabolism associated with infection or failures of various organ systems.
Hypoglycemia is treated rapidly by restoring the blood glucose level to normal by the ingestion or administration of dextrose or carbohydrate foods quickly digestible to glucose. In some circumstances it is treated by injection or infusion of glucagon. Prolonged or recurrent hypoglyemia may be prevented by reversing or removing the underlying cause, by increasing the frequency of meals, with medications like diazoxide, octreotide, or glucocorticoids, or even by surgical removal of much of the pancreas.
The level of blood glucose low enough to define hypoglycemia may be different for different people, in different circumstances, and for different purposes, and occasionally has been a matter of controversy. Most healthy adults maintain fasting glucose levels above 70 mg/dL (3.9 mmol/L), and develop symptoms of hypoglycemia when the glucose falls below 55 mg/dL (3 mmol/L).
It can sometimes be difficult to determine whether a person's symptoms are due to hypoglycemia. Endocrinologists (physicians with expertise in disorders of glucose metabolism) typically consider the criteria referred to as Whipple's triad as conclusive evidence that an individual's symptoms can be attributed to hypoglycemia instead of to some other cause:
Hypoglycemia (alternative medicine) is also a term in popular culture and alternative medicine for a common, often self-diagnosed condition characterized by shakiness and altered mood and thinking, but without measured low glucose or risk of severe harm. It is treated by changing eating patterns.