Diabetes mellitus is a relatively common disease of the endocrine system and can have a variety of dermatologic changes. Itchy skin is one of the more common skin complications in diabetic patients, and is often used as the first diagnostic clue to diagnose diabetes through further examination. The mechanism of itchy skin complicating diabetes mellitus is not well defined, and dry skin is an important cause of its development. Long-term hyperglycemia in diabetic patients leads to dry skin, poor elasticity, and disruption of the barrier function, which increases the likelihood of itchiness. In addition, diabetes mellitus can be complicated by polyneuropathy or peripheral neuropathy, which can cause itching of the trunk. In some patients, metabolic abnormalities in the body may lead to secondary infections, such as bacterial, fungal or viral infections, which aggravate skin damage and cause itching. Symptomatic treatment should be given according to the different situations to reduce the patient’s symptoms and improve the patient’s quality of life.