Hypoglycemia, or low blood sugar, is a fasting blood sugar less than 55 mg/dl. According to "Harrison's Principles of Internal Medicine," the diagnosis is best made when low blood sugar is accompanied by symptoms of hypoglycemia. These symptoms subside after blood glucose levels are raised. Symptoms of hypoglycemia include sweating, anxiety and confusion.
Medications
Medications used to treat diabetes can cause hypoglycemia when taken accidentally or intentionally by non-diabetics. Alcohol leads to low blood sugar in certain circumstances. Hypoglycemia typically occurs in alcoholics after a multi-day alcohol binge. Glucose can be produced for several days from breakdown of other substances in the body, but eventually production of glucose by the liver needs to kick in. Alcohol interferes with production of new glucose by the liver and thus a prolonged binge can lead to hypoglycemia. Other drugs such as quinidine and salicylates can also cause hypoglycemia.
Critical Illness
Serious illnesses such as heart, liver or kidney failure, and sepsis often cause hypoglycemia. The cause for hypoglycemia in these conditions is complicated and involves a failure to produce enough glucose, over-utilization by the body and hormonal changes. For example, in renal failure, the rate of insulin excretion decreases and excess insulin leads to hypoglycemia.
Tumors
Insulinomas are tumors that produce insulin independently of the body's need for it, secreting insulin even when blood sugar is low, thus causing hypoglycemia. These tumors are rare, occurring in one in 250,000 people every year, as explained in "Harrison's Principles of internal Medicine." Though usually benign, they can lead to death from hypoglycemia. Sometimes these tumors appear as part of a syndrome with other types of endocrine tumors.
Reactive Hypoglycemia
Also known as postprandial hypoglycemia, this type of hypoglycemia occurs after meals. Causes include a gastrectomy, which is removal of part or all of the stomach, but for the most part the cause is unknown. According to the National Institutes of Health, various hormones have been implicated in this condition, such as a deficiency in glucagon, a hormone that raises blood sugar levels.
References
- "Harrison's Principles of Internal Medicine, 17th edition"; Anthony Fauci et al.; 2008
- National Institutes of Health: Hypoglycemia
