Hypoglycemia refers to a syndrome characterized by symptoms of sympathetic nerve excitation and brain cell hypoxia due to low blood glucose concentration. We usually identify hypoglycemia first by a series of symptoms. The primary symptoms of hypoglycemia are sympathetic nerve symptoms, including dizziness, palpitations, cold sweats, hunger, and pallor. If these symptoms occur, we use a glucometer to determine if the blood sugar level is below 2.8 mmol/L. If the blood sugar is below 2.8 mmol/L, one should quickly consume sugary water and energy. If the patient's symptoms are alleviated, then it is considered hypoglycemia.