Idiopathic hypoglycemia
Idiopathic or
common hypoglycemia is a condition in which the glucose level in the blood is abnormally low. Unlike other forms of hypoglycemia, this variety is not caused by medication, drugs, or illness. ("Idiopathic" is medicalese for "we don't know what causes it!")
This reviser suggests that the two conditions described below are NOT "idiopathic" hypoglycemia because the mechanism for the low glucose is known and precisely defined; they are simply two among the hundreds of causes of hypoglycemia which are understood to some degree. After the opening sentences above, the content of this article nearly completely evades both the denoted and the implied subject of the title. Lest this criticism seem obscure, let me spell it out. To those with the most extensive training and experience with the varieties of severe hypoglycemia, hypoglycemia denotes symptoms caused by blood glucose levels measurably lower than those of similar healthy people and the term idiopathic hypoglycemia denotes such hypoglycemia when it does not fall into one of the "medically understood" forms. However these are rare and obscure and by being "idiopathic" are not susceptible to much illumination. However most professional and lay readers would expect from the title a discussion of the symptom complex popularly referred to in our society as "hypoglycemia." It has many unsatisfactory designations, such as functional hypoglycemia and "nonhypoglycemia," and is the kind of hypoglycemia most often described by websites. One of its characteristics is that the association of symptoms with measured low blood glucose is sometimes nil. This is a controversial, interesting, and difficult topic worth more than an explanation of the word idiopathic.
Postprandial, or reactive, hypoglycaemia
When we eat a meal, we secrete insulin to move the sugars from the blood to the body's cells. In some people the insulin secretion "overshoots" and their blood-sugar level can get low enough after meals to produce mild to moderate hypoglycemic symptoms. Postprandial hypoglycemia may occur with lunch-time meals that include foods high in sugar or carbohydrate and can be exacerbated by alcohol. The condition can be managed so that hypoglycemia is prevented or ameliorated by including foods in the meal that slow digestion and stomach emptying (typically fat and protein) or by slowing the digestion of starch with a glucosidase inhibitor such as acarbose.
Original contributor wrote: "...but may not be detected because it is fairly uncommon and may not be recognized." In fact, reactive hypoglycemia is probably the best known and most easily recognized form of hypoglycemia by primary physicians and persons without medical training.
A prolonged glucose tolerance test can help detect the condition. There have been "fad" books claiming that a large number of bizarre symptoms are caused by this condition (e.g., UFO sightings and criminal behavior).
Original contributor wrote: "The "real" symptoms can be serious enough, for example if the person loses consciousness while driving a car." In fact, reactive hypoglycemia in adults very rarely results in loss of consciousness (this reviser has never heard of an instance). For the vast majority of adults, reactive hypoglycemia is a nuisance reduced or avoided by changing eating habits, at least compared to the life- or brain-threatening hypoglycemia of insulinomas, congenital hyperinsulinism, insulin taken for diabetes, etc.
Insulin secreting tumours
A potentially serious form of hypoglycaemia is caused by an insulin-secreting tumour of the pancreas. In this condition there are high levels of insulin despite blood sugar being low. The severity of hypoglycemia can range from mild symptoms to seizures, unconsciousness and even death.