The most common symptoms of high blood sugar are three more and one less, that is, dry mouth, excessive drinking, excessive urination and wasting, and some patients will show dizziness, if the blood sugar is very high and the blood supply to the brain is insufficient, dizziness will appear. Some people have special manifestations of high blood sugar, such as numbness in the limbs, cotton-like sensation, or pins and needles, as well as unclear vision, or sudden loss of vision, or skin problems, such as itchy vulva, itchy skin, or allergy-like petechiae on both lower limbs, or even bubble-like urine in some patients. If the blood sugar is particularly high, there will also be chest tightness, palpitations, nausea, vomiting, and even some people will suddenly feel a crushing pain in the heart, which are all manifestations of high blood sugar.