Patients with type 2 diabetes mellitus combined with diabetic foot always spit, which may be caused by upper respiratory tract infection, chronic bronchitis, bronchiectasis and other diseases. 1. Acute upper respiratory tract infection: for example, acute viral pharyngitis, chronic pharyngitis, etc., the respiratory mucosa may have inflammatory reaction, resulting in increased mucus secretion and phlegm. 2. Chronic bronchitis, bronchiectasis: chronic bronchitis can have symptoms such as coughing, coughing up sputum, wheezing; while bronchiectasis can have coughing, sputum and hemoptysis. Patients with type 2 diabetes combined with diabetic foot always spit up, it is recommended to go to the hospital, ask the doctor to make a judgment, clarify the cause of the disease and treatment.