Hypoglycemia is a condition in which levels of glucose in the blood are abnormally low. According to the National Diabetes Information Clearinghouse, there are two types of non-diabetic hypoglycemia--fasting hypoglycemia, occurring after a period of not eating or intense exercise, and reactive hypoglycemia, occurring within a few hours of a meal. While reactive hypoglycemia may be the result of abnormal glucose metabolism or heightened hormonal sensitivity, fasting hypoglycemia is more likely to be caused by underlying hormonal or medical problems.
Abnormal Sugar Metabolism
According to Merck, some people may develop fasting hypoglycemia as a result of underlying medical problems that interfere with the body's ability to maintain normal blood glucose levels. For example, heavy drinkers may become hypoglycemic because alcohol can inhibit the release of glucose by the liver into the bloodstream. Other liver diseases like hepatitis, cancer or cirrhosis can also interfere with sugar storage.
The National Diabetes Information Clearinghouse also notes that some people may develop reactive hypoglycemia as a result of deficiencies in the secretion of glucagon--a hormone involved in the metabolism of sugar.
Hormonal Imbalances
Medical conditions that affect the normal production and balance of hormones in the body can cause hypoglycemia. Hyperinsulinism--a state in which there is too much insulin hormone in the bloodstream--can occur as a result of a tumor in the pancreas. According to the Merck Manuals Online Medical Library, a pancreatic tumor may cause fasting hypoglycemia, stimulating the secretion of large amounts of insulin in the presence of low blood sugar after a period of not eating.
Other disorders such as Addison's disease that affect the secretion of hormones by the pituitary and adrenal glands can also cause hypoglycemia. Heart failure, kidney failure, certain cancers and shock--a life-threatening condition characterized by lack of sufficient blood flow--may also interfere with normal hormone production and balance and lead to hypoglycemia, according to Merck.
It is theorized that even normal hormone secretion can cause hypoglycemia in certain people. In particular, some speculate that reactive hypoglycemia may be caused by an overly sensitive response to epinephrine, according to the National Diabetes Information Clearinghouse. Epinephrine is a hormone that is released naturally when blood sugar levels drop. It causes symptoms that resemble anxiety, including sweating, rapid heartbeat, nervousness and lightheadedness. Though a normal response, some individuals may have an abnormal response to its release.
Medications
Certain medications may occasionally cause hypoglycemia. Pentamidine--an antimicrobial drug commonly used to treat Pneumocystis pneumonia (a type of AIDS-related pneumonia)--and quinine--a drug used in the treatment of malaria--are examples of drugs that can induce abnormally low blood sugar, according to Merck.
Uncommon Causes
According to the National Diabetes Information Clearinghouse, reactive hypoglycemia may rarely be caused by stomach surgery that causes food to pass rapidly into the small intestine. Inherited deficiencies in certain enzymes--for example, a condition in which a lack of normal enzymes causes fructose intolerance--can also cause reactive hypoglycemia.
