Overt diabetes mellitus caused by the topical administration of dexamethasone ointment on the oral mucosa.

We herein describe the case of a 68-year-old man who developed overt diabetes mellitus following the topical administration of dexamethasone 0.1%-containing ointment over a five-month period to treat oral lichen planus. The topical dexamethasone therapy was discontinued gradually, and the patient was subsequently treated with insulin for one month without clinical signs of overt adrenal insufficiency. An oral glucose tolerance test revealed impaired glucose tolerance after the treatment. The potential for the deterioration of glucose metabolism must be considered when patients with impaired glucose tolerance are treated with relatively low doses of topical corticosteroid ointment on the oral mucosa, even for short periods.