Diabetes mellitus.

Dermatologic problems are common in diabetes, with approximately 30% of patients experiencing some cutaneous involvement during the course of their illness. Skin manifestations generally appear during the course of the disease in patients known to have diabetes, but they may also be the first presenting sign of diabetes or even precede the diagnosis by many years. The skin involvement can be autoimmune in nature, such as acanthosis nigricans, necrobiosis lipoidica, diabetic dermopathy, scleredema, and granuloma annulare, or infectious in the form of erythrasma, necrotizing fasciitis, and mucormycosis. Pharmacologic management of diabetes, in addition, can also result in skin changes, such as lipoatrophy and lipohypertrophy, at the site of injection of insulin, and oral antidiabetic agents can cause multiple skin reactions as adverse effects. The management of these cutaneous manifestations is tailored according to the underlying pathophysiology, but a tight control of blood glucose is a prerequisite in all management strategies.