Factors causing high blood glucose mainly include improper diet, stress and impaired pancreatic function. 1. Improper diet: a one-time large intake of sweets leads to the body can not compensate for the transient increase in blood glucose, long-term diet will lead to insulin secretion disorders, and ultimately lead to pancreatic dysfunction, insulin deficiency, resulting in diabetes mellitus. 2. Stress: In the case of burns, severe trauma, severe infections and other stressful situations, the body adrenaline, glucocorticoid and other glucagon hormones rise, resulting in increased blood glucose. 3. Impaired pancreatic function: such as pancreatitis, pancreatic injury leads to insufficient pancreatic secretion of insulin, insulin as the body’s only hormone that can lower blood glucose, insufficient secretion will cause an increase in blood glucose. The main reasons for high blood sugar are as mentioned above, patients with high blood sugar should go to the hospital in time to improve the examination and give targeted treatment after the cause is clear.