There are two cases of diabetes mellitus when glucocorticoids are used: firstly, those who have latent or clinical diabetes mellitus, whose condition is induced or aggravated after glucocorticoid treatment; secondly, those who have purely adverse reactions to glucocorticoids, i.e. secondary diabetes mellitus. If the condition permits, glucocorticoid dosage should be reduced as much as possible and immunosuppressive drugs should be added. In these patients, fasting blood sugar returns to normal after glucocorticoid reduction or discontinuation. For patients with active disease who must be treated with glucocorticoids, if fasting blood glucose and 2 hours postprandial blood glucose are high, diet can be controlled and insulin and other hypoglycemic drugs can be used in combination with glucocorticoid treatment.