Symptoms of hypoglycemia include sympathetic hyperexcitability and central nervous system dysfunction. Causes include physiologic underfeeding, or pathologic insulinoma, hypoadrenalism, and hypoglycemic drug overdose. 1.Symptoms: (1) Sympathetic overexcitation: hypoglycemia causes an increase in norepinephrine, etc., which is manifested as panic, sweating, shaking hands, pallor, and hunger. (2) Central nerve dysfunction: it refers to the dysfunction that occurs when brain cells lack glucose, including slow thinking, poor concentration, drowsiness and coma. 2.Causes: (1) Physiological underfeeding: hypoglycemia can occur when blood glucose is consumed excessively by exercise, etc., and food is not replenished in time, or when food cannot be eaten due to disease, etc. (2) Insulinoma: it is the excessive secretion of insulin due to the over proliferation of pancreatic β-cells or pancreatic β-cell tumor. Typical symptoms are recurrent episodes of hypoglycemia, prone to psychiatric symptoms, and episodes occurring mostly during fasting. (3) Hypoadrenalism: It refers to the insufficiency of adrenal glands due to inflammation, autoimmune and other factors, which causes the decrease of cortisol, which has the effect of raising glucose, so the decrease of cortisol when the adrenal glands are hypoadrenalized can cause hypoglycemic episodes. (4) Overdose of hypoglycemic drugs: diabetic patients applying hypoglycemic drugs or overdose of insulin can cause blood glucose to drop, and hypoglycemia can occur when they fail to replenish food in time. Once the symptoms of hypoglycemia appear, you should immediately sublingual sugar cubes or eat high-energy food, and then go to the hospital in time to avoid fainting and other dangers.