Hypoglycemia

Hypoglycemia is a medical term referring to a pathologic state produced by a lower than normal amount of sugar (glucose) in the blood. The term hypoglycemia literally means "low blood sugar". 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). Derangements of function can range from vaguely "feeling bad" to coma and (rarely) death. Hypoglycemia can arise from many causes, and can occur at any age. The most common forms of moderate and severe hypoglycemia occur as a complication of treatment of diabetes mellitus with insulin or oral medications.

Endocrinologists (specialists in disorders of blood glucose metabolism) typically consider the following criteria (referred to as Whipple's triad) as proving that an individual's symptoms can be attributed to hypoglycemia:

Symptoms known to be caused by hypoglycemia
Low glucose at the time the symptoms occur
Reversal or improvement of symptoms or problems when the glucose is restored to normal
However, not everyone has accepted these suggested diagnostic criteria, and even the level of glucose low enough to define hypoglycemia has been a source of controversy in several contexts. For many purposes, plasma glucose levels below 70 mg/dl or 3.9 mmol/L are considered hypoglycemic

Treatment and prevention
Management of hypoglycemia involves immediately raising the blood sugar to normal, determining the cause, and taking measures to prevent future episodes.

Reversing acute hypoglycemia
The blood glucose can be raised to normal within minutes by taking (or receiving) 10-20 grams of carbohydrate. It can be taken as food or drink if the person is conscious and able to swallow. This amount of carbohydrate is contained in about 3-4 ounces (100-120 ml) of orange, apple, or grape juice, about 4-5 ounces (120-150 ml) of regular (non-diet) soda), about one slice of bread, about 4 crackers, or about 1 serving of most starchy foods. Starch is quickly digested to glucose, but adding fat or protein retards digestion. Symptoms should begin to improve within 5 minutes, though full recovery may take 10-20 minutes. Overfeeding does not speed recovery and if the person has diabetes will simply produce hyperglycemia afterwards.

If a person is suffering such severe effects of hypoglycemia that they cannot (due to combativeness) or should not (due to seizures or unconsciousness) be given anything by mouth, glucose can be given by intravenous infusion or the glucose can be rapidly raised by an injection of glucagon. Further details of glucagon use are provided in the article on diabetic hypoglycemia.

Preventing further episodes
The most effective means of preventing further episodes of hypoglycemia depends on the cause.

The risk of further episodes of diabetic hypoglycemia can often be reduced by lowering the dose of insulin or other medications, or by more meticulous attention to blood sugar balance during unusual hours, higher levels of exercise, or alcohol intake.

Many of the inborn errors of metabolism require avoidance or shortening of fasting intervals, or extra carbohydrates. For the more severe disorders, such as type 1 glycogen storage disease, this may be supplied in the form of cornstarch every few hours or by continuous gastric infusion.

Several treatments are used for hyperinsulinemic hypoglycemia, depending on the exact form and severity. Some forms of congenital hyperinsulinism respond to diazoxide or octreotide. Surgical removal of the overactive part of the pancreas is curative with minimal risk when hyperinsulinism is focal or due to a benign insulin-producing tumor of the pancreas. When congenital hyperinsulinism is diffuse and refractory to medications, near-total pancreatectomy may be the treatment of last resort, but in this condition is less consistently effective and fraught with more complications.

Hypoglycemia due to hormone deficiencies such as hypopituitarism or adrenal insufficiency usually ceases when the appropriate hormone is replaced.

Hypoglycemia due to dumping syndrome and other post-surgical conditions is best dealt with by altering diet. Including fat and protein with carbohydrates may slow digestion and reduce early insulin secretion. Some forms of this respond to treatment with a glucosidase inhibitor, which slows starch digestion.

Reactive hypoglycemia with demonstrably low blood glucose levels is most often a predictable nuisance which can be avoided by consuming fat and protein with carbohydrates, by adding morning or afternoon snacks, and reducing alcohol intake.

Idiopathic postprandial syndrome without demonstrably low glucose levels at the time of symptoms can be more of a management challenge. Many people find improvement by changing eating patterns (smaller meals, avoiding excessive sugar, mixed meals rather than carbohydrates by themselves), reducing intake of stimulants such as caffeine, or by making lifestyle changes to reduce stress. See the following section of this article.

Hypoglycemia as American folk medicine
Hypoglycemia is also a term of contemporary American folk medicine which refers to a recurrent state of symptoms of altered mood and cognitive efficiency, sometimes accompanied by adrenergic symptoms, but not necessarily by measured low blood glucose. Symptoms are primarily those of altered mood, behavior, and mental efficiency. This condition is usually treated by dietary changes which range from simple to elaborate.

This condition therefore overlaps with the definition and forms of hypoglycemia described in the remainder of this article but is not entirely congruent. When low glucose levels can be measured, this condition is what is usually described by physicians as idiopathic reactive hypoglycemia. When glucose levels are not low enough to distinguish the patient's glucose from normal levels, this type of "hypoglycemia" does not carry the same risks of coma or brain damage as measurable hypoglycemia that meets the Whipple criteria. A variety of terms have been used in the medical literature: functional hypoglycemia, idiopathic postprandial syndrome, pseudohypoglycemia, nonhypoglycemia, and "hypoglycemia". The terms range from favorable to pejorative and reflect the range of attitudes of physicians as much as the nature of the condition.

Advising people on management of this condition is a significant "sub-industry" of alternative medicine. More information about this form of "hypoglycemia", with far more elaborate dietary recommendations, is available on the internet and in health food stores. Most of these websites and books describe a conflated mixture of reactive hypoglycemia and idiopathic postprandial syndrome but do not recognize a distinction. The value of these recommendations is unproven.