Patient was instructed on hypoglycemia. Hypoglycemia may result from a variety of causes, which include: Spontaneous reactive hypoglycemia. Symptoms of hypoglycemia within 1 to 2 hours after a meal in people who have not had stomach surgery is called spontaneous reactive hypoglycemia. It also is sometimes called functional or idiopathic hypoglycemia. In many cases, it is difficult to verify that the symptoms are caused by low blood sugar.