The effect of dexamethasone on blood sugar usually lasts 1-2 weeks. Dexamethasone is a long-acting adrenocorticotropic hormone drug, which has a greater effect on blood sugar after use. Dexamethasone is a modified adrenocorticotropic hormone, which is a strong glucose-raising hormone. After use, if abnormal glucose metabolism occurs, you should promptly go to the endocrinology department for consultation and treatment. If the patient is already at risk of diabetes, or is originally a patient with impaired fasting glucose or reduced glucose tolerance, blood glucose may easily rise after using dexamethasone, resulting in secondary diabetes, and for such patients, a combination of insulin and oral hypoglycemic drugs is required. Dexamethasone is mainly used to treat certain allergic diseases, systemic lupus erythematosus and other autoimmune diseases. In the process of using it, it must be carried out according to medical advice. The amount of hormone will be relatively large at the beginning of use, but it should be gradually reduced when it is withdrawn, and the adrenocorticotropic hormone should not be reduced rapidly, otherwise it will easily cause other problems in the organism. Patients must follow medical advice in the process of using dexamethasone. Patients are not recommended to adjust or apply dexamethasone by themselves because many side effects can occur in the process of hormone use, including the appearance of full moon face, buffalo back, centripetal obesity, hypertension, stress ulcers and some psychiatric symptoms.