Dry mouth, bitter mouth may be seen in the following diseases: 1, diabetes: patients with increased blood sugar will have dry mouth, bitter mouth, want to drink water at night, dry mouth during the day, more urine, etc., may also appear to eat more, but the weight is still dropping, this time need to carry out a glucose tolerance test to confirm the diagnosis of whether there is diabetes mellitus; 2, hyperthyroidism: hyperthyroidism patients with high metabolic rate, the body is always in a state of water shortage, the This makes people feel dry mouth and bitter mouth, so they can check the thyroid function to know whether there is any abnormality in the thyroid function. Hyperthyroidism patients often have panic, palpitations, while the skin is moist, eyes are more attractive, even eyeballs protruding and other symptoms; 3, dry syndrome: belongs to the immune disease, dry syndrome patients with oral glands function decline, and even the whole body gland secretion function decline, appeared to be more dry mouth, bitter mouth, and may be sad when there is no tears out of the eyes, you can check the rheumatism and immunity related indicators to confirm the diagnosis; 4.Helicobacter pylori infection: the reflux of stomach contents leads to discomfort in the mouth.