The common causes of high blood glucose in the morning are considered in terms of irrational use of drugs, dawn phenomenon, and Sumuje reaction. 1. Unreasonable use of medication, insufficient dosage of hypoglycemic drugs at night may cause high blood glucose in the morning. 2. Dawn phenomenon, the main reason for dawn phenomenon is the increase of growth hormone in the body after midnight, growth hormone can increase blood glucose, and more insulin is needed to maintain blood glucose in the normal range. 3. Sumuje reaction, Sumuje reaction refers to the occurrence of hypoglycemia at night, and in the early morning hypoglycemia stimulates the secretion of glucagon, resulting in reactive blood glucose increase. For patients with high blood glucose in the morning, it is recommended to consult a doctor in time and follow the doctor’s instructions.