Diabetic patients generally refers to the blood glucose concentration exceeds a certain value, diabetic patients generally do not appear to have a sweet mouth, if high blood glucose leads to acute complications of diabetes, such as diabetic ketoacidosis, instead, there will be a bitter mouth, or even the taste of rotten apples. If the saliva is sweet, usually not considered diabetes caused. Diabetic patients with high blood glucose concentration may cause symptoms of dry mouth, will stimulate the drinking center so that the patient to drink more water, dry mouth after drinking more water, thus causing polyuria, because diabetic patients with high blood glucose, it will cause osmolality increase, so the general performance of the patient with a dry mouth is the main, and generally will not appear in the case of sweet mouth.