Drinking a lot of water every day or being dehydrated is common in two diseases: the first is diabetes, which is called thirst in Chinese medicine, and its typical symptoms are three more and one less, that is, eating more, drinking more and urinating more, accompanied by weight loss. In case of diabetes, the dry mouth will be relieved after glucose-lowering treatment. In addition to dry mouth and eyes, there is also dry skin, which cannot be relieved by drinking a lot of water. Both of these diseases need to be diagnosed by blood tests and urine retention.