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!")

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 this mechanism overshoots and their blood-sugar level can get dangerously low after meals. This situation most commonly occurs with lunch-time meals that include foods high in sugar or carbohydrate and can be exacerbated by alcohol. The condition can be corrected, but may not be detected because it is fairly uncommon and may not be recognized.

A prolonged glucose tolerance test can help detect the condition. There have be been "fad" books claiming that a large number of bizarre symptoms are caused by this condition. The "real" symptoms can be serious enough, for example if the person loses consciousness while driving a car.

Insulin secreting tumours

A potentially serious form of idiopathic 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.