Hypoglycemia: Low blood sugar (glucose). Hypoglycemia may be associated with symptoms such as anxiety, sweating, tremor, palpitations, nausea, and pallor. Hypoglycemia also starves the brain of glucose energy, which is essential for proper brain function. Lack of glucose energy to the brain can cause symptoms ranging from headache, mild confusion, abnormal behavior, loss of consciousness, seizure, and coma. Severe hypoglycemia can cause death. The causes of hypoglycemia include use of drugs (such as insulin), liver disease, surgical absence of the stomach, tumors that release excess amounts of insulin, and pre-diabetes. In some patients, symptoms of hypoglycemia occur during fasting (fasting hypoglycemia). In others, symptoms of hypoglycemia occur after meals (reactive hypoglycemia). Immediate treatment of severe hypoglycemia consists of administering large amounts of glucose and repeating this treatment at intervals if the symptoms persist. Treatment must also be directed at the underlying cause. Treatment of reactive hypoglycemia involves changing the diet, including eating fewer concentrated sweets and ingesting multiple small meals throughout the day.