“Hypoglycaemia” is the medical term for low blood sugar (glucose).

Occasionally, hypoglycaemia can be dangerous (for example, from injecting too much insulin). It may also indicate a serious underlying medical condition, such as a tumour of the pancreas or liver disease. More often, however, when people say they have hypoglycaemia, they are describing a group of symptoms that occur when the body overreacts to the rise in blood sugar that occurs after eating, resulting in a rapid or excessive fall in the blood sugar level. This is sometimes called “reactive hypoglycaemia.”

Many people who believe they have reactive hypoglycaemia do not, in fact, have low blood sugar levels,¹ and many people who do have low blood sugar levels do not have any symptoms of reactive hypoglycaemia.² Some evidence suggests that reactive hypoglycaemia may be partly a psychological condition.³ Consequently, some doctors believe that reactive hypoglycaemia does not exist.⁴ Most doctors, on the other hand, have found reactive hypoglycaemia to be a common cause of the symptoms listed below.