“High blood glucose just after waking up” generally refers to high fasting blood glucose level. The causes of high fasting blood glucose in diabetic patients may be irrational use of medication, dawn phenomenon, Sumuj reaction, stress reaction and so on. 1. Unreasonable medication: Insufficient insulin application at night in diabetic patients may lead to high fasting blood glucose. Fasting blood glucose can be lowered by increasing the dose of insulin at bedtime, and monitoring of blood glucose changes at night is needed. 2. Dawn phenomenon: i.e., good glycemic control at night and no hypoglycemia, only transient hyperglycemia at dawn, which may be due to excessive secretion of free cortisol, growth hormone, etc. in the early morning. 3. Sumuje reaction: hypoglycemia has appeared at night, but it is not noticed during sleep, which is due to the increased secretion of insulin-antagonist hormones in the body, which in turn causes rebound blood glucose elevation. 4. Stress response: diabetic patients with infections, surgeries, and trauma may also experience elevated fasting blood glucose. It is recommended that diabetic patients with high fasting blood glucose level should go to regular hospitals in time to improve the relevant examinations under the guidance of doctors and standardize the treatment so as to avoid delaying the condition.