Clinical beta-blockers for the treatment of accelerated heart rate are again most commonly used with propranolol, or what we refer to as the heartburn. Numerous studies have proven that propranolol is associated with hypoglycemia, especially in cases of malnutrition, anesthesia and heavy use of insulin, and is particularly likely to cause hypoglycemia. The mechanism of its action is: to make the catecholamine effect is weakened, causing hepatic glycogenolysis is blocked, reducing hepatic sugar output and gluconeogenesis, and can inhibit fatty acids, reduce the blood glucagon level, and cause hypoglycemia by reducing blood glucose production. Another point to note is that because propranolol slows down the heart rate and tends to mask the symptoms of tachycardia caused by catecholamines and sympathetic excitation due to hypoglycemia, the symptoms of hypoglycemia are often atypical and inconspicuous, and are easily overlooked or even misdiagnosed. Relatively speaking, newer beta-blockers, which have less effect on blood glucose, such as metoprolol, bisoprolol, etc., but it is also necessary to pay attention to monitoring blood glucose. It is recommended that if a beta-blocker is applied with a risk of hypoglycemia, care must be taken to review blood glucose to avoid masking symptoms and danger.