Secondary diabetes mellitus may occur after prolonged high-dose administration of methylprednisolone, and may be reversible after discontinuation of the drug. Methylprednisolone is a synthetic glucocorticoid, which can play the role of anti-inflammatory, anti-allergic, etc. It can be used to treat immune disorders, severe urticaria, psoriasis and other skin diseases, and severe allergic diseases difficult to deal with by conventional therapy. It should not be used in patients who are allergic to methylprednisolone, systemic fungal infections and so on. After using the drug, there will be an increase in blood glucose, but also stress ulcers, bleeding, perforation and other digestive symptoms, excitement, insomnia and other psychiatric symptoms; short-term use of hormone-induced blood glucose elevation of small doses can generally be recovered after discontinuation of the drug, but long-term use of hormone doses may be difficult to recover after discontinuation of blood glucose, resulting in diabetes mellitus. Patients who need to use methylprednisolone treatment should be under the guidance of a doctor.