Some diabetic patients may have no obvious symptoms, while others may have three more and one less symptom, symptoms of acute complications and chronic complications. 1. Three more and one less symptom: The typical symptoms of diabetes mellitus are “three more and one less”, which are: polyuria, which refers to the increased frequency of urination; polydipsia, which refers to the feeling of dryness of the mouth, and the increase in the amount and frequency of water consumption compared with the patient’s normal period; polyphagia, which refers to the feeling of hunger, and the feeling of hunger again soon after eating; and oligophagia, which refers to the unexplainable loss of body weight. 2. Symptoms of acute complications: acute complications mainly include hyperosmolar hyperglycemic coma and ketoacidosis, which can be manifested as coma, severe dehydration, decreased urine output, decreased blood pressure, accelerated heart rate, cold limbs (cold limbs, even to the elbows and above the knees), and impaired consciousness. 3. Chronic complications: blurred vision, severe blindness; symmetrical sensory abnormalities in the distal part of the hands and feet, with glove and sock-like distribution, and loss of sensation at a later stage; pain and discomfort in the lower limbs when walking; and ulceration of the feet after trauma. When there is complication of heart, brain and kidney diseases, there can be corresponding symptoms, such as chest tightness, dizziness, proteinuria and so on. If patients have the above symptoms, they need to go to the hospital in time, and follow the doctor’s instructions to carry out the corresponding examination and treatment.