The clinical manifestations of type 2 diabetes are very complex and diverse, not simply showing three more and one less, i.e., drinking more, eating more and urinating more. The differential diagnosis of diabetes mellitus in Chinese medicine includes upper elimination, middle elimination and lower elimination, as follows: 1. Upper elimination: mostly manifests as dry mouth and thirst, excessive drinking, dry mouth and tongue, and frequent urination; 2. Middle elimination: mainly manifests as being able to eat, easy hunger, thin shape, dry stool, and bad breath; 3. Lower elimination: mostly seen in type 2 diabetes mellitus patients with longer disease duration, frequent urination, weakness of waist and knees, dizziness, and memory loss. It is necessary to distinguish thirst or dry syndrome from type 2 diabetes. The blood sugar of patients with thirst and dry syndrome is normal whether fasting or postprandial blood sugar. When patients feel dry mouth, thirst and hunger, it is better to go to the hospital to test fasting blood sugar or postprandial blood sugar to confirm the diagnosis and take appropriate treatment.