Diabetes is a group of diseases characterized by elevated blood glucose. The main pathophysiological changes are persistent hyperglycemia and long-term metabolic disorders, which can eventually lead to damage to the eyes, kidneys, cardiovascular and nervous systems and their dysfunction and failure, but the damage is a chronic progressive process with different symptoms at different stages. Early stage of diabetes: The most important feature is that there are no symptoms. Patients can only find elevated blood glucose during the examination. When the disease is short or the elevated blood glucose is limited, there can be no clinical symptoms at all, but there is no specific indicator of how high the specific blood glucose is before symptoms start to appear, and each patient has great specificity. Typical symptoms: The most common are the three symptoms of polyhydramnios, namely polyhydramnios, polyphagia, polyuria and wasting. This is caused by the increase of osmotic pressure due to blood glucose in the blood, which causes thirst for water; due to the relative or absolute lack of insulin, which causes the glucose in the body not to be used, protein and fat consumption will increase, thus causing thirst, weakness and weight loss; the body eats more because of hunger in order to compensate for the lost sugar and maintain the body’s activities. Atypical symptoms: Some patients with type 2 diabetes have atypical symptoms, only dizziness, weakness, etc., and may even have no symptoms. In some cases, symptoms of hypoglycemia before lunch or dinner may occur early in the onset of diabetes or in the prediabetic phase. The common characteristic is mainly that there is no characteristic, and clinically patients usually visit the clinic with other symptoms and find the abnormality of blood sugar by chance. Acute complications: The condition of diabetic patients may suddenly aggravate under stress and other circumstances, generally due to the abnormal osmotic pressure of the body caused by the rapidly increasing blood sugar, which then causes corresponding effects in different organs, and may result in loss of appetite, vomiting, nausea, abdominal pain, aggravation of polyuria, drowsiness, blurred vision, dizziness, difficulty in whistling, hyperosmolar coma, ketoacidosis, etc. Chronic complications: Generally, they only occur in patients with long-term hyperglycemia, but there are also patients who come to the first consultation for complications because the primary symptoms are not obvious. Commonly, there are diabetic fundus retinopathy, diabetic nephropathy, diabetic neuropathy, recurrent infections, diabetic foot, pruritus, atherosclerotic lesions of heart, brain and kidney vessels, combined with hypertension, etc. Therefore, the damage of diabetes is very extensive, and the clinical manifestations vary at different stages, and there are even no symptoms in the early stage, so regular blood sugar check is the key to early detection and treatment.