High blood glucose means that the blood glucose value is higher than the normal range. A normal fasting blood glucose is less than 6.1 mmol/L and a normal two-hour postprandial blood glucose is less than 7.8 mmol/L. If it is higher than this range, it is usually high. Slightly elevated blood glucose may be due to physiological reasons such as emotional stress, and can usually be recovered after calming down. Significantly elevated blood glucose is most common in people with diabetes. Diabetes mellitus is a metabolic disease characterized by elevated blood glucose, which is caused by impaired insulin secretion or impaired biological function of insulin. Prolonged hyperglycemia increases the risk of impaired cardiac, cerebral, renal, and vascular function, and needs to be treated aggressively. In addition, patients with chronic pancreatitis and patients with liver disease may also have abnormal regulation of glucose metabolism, which may cause elevated blood glucose. Regardless of which disease causes elevated blood glucose, you should actively carry out the appropriate examination, cooperate with the doctor to standardize the treatment, try to control the development of the disease and improve the quality of life.