Diabetic patients with blood glucose elevated to 20mmol/L, may be related to eating too much high-sugar food, may also be caused by irregular use of hypoglycemic drugs, or stress can also lead to elevated blood glucose. 1. Eating too much high-sugar food: diabetic patients who do not control their diets and consume too much high-sugar food or high-calorie food, such as all kinds of sugary drinks, cakes, fatty meats, etc., may lead to a significant increase in blood glucose values, which may reach 20 mmol/L. 2. Irregular use of hypoglycemic drugs: If a diabetic patient forgets to take oral hypoglycemic drugs or forgets to inject insulin, it may also lead to the problem of elevated blood glucose levels. 3. State of stress: Patients who are subjected to stressful stimuli, such as burns, trauma or surgery, may also experience a significant increase in blood glucose levels. When the blood glucose level rises to 20mmol/L, acute complications of diabetes such as diabetic ketoacidosis and hyperosmolar hyperglycemia syndrome may occur, and it is recommended that the patient consults the endocrinology department of a regular hospital, and actively cooperates with the physician for treatment.