With the improvement of living standards, diabetes is becoming one of the main diseases that endanger the health of the population. Many people often “think of the disease by its name”, thinking that diabetes is the discharge of sugar in the quiet, no sugar in the urine is not diabetes, in fact, this understanding is wrong. Diabetes mellitus is a common endocrine metabolic disease, which can be asymptomatic in the early stage, but further development can lead to polyphagia, polydipsia, polyuria, and lethargy, which are all caused by the disorder of glucose metabolism in the body, and laboratory tests show hyperglycemia, reduced glucose tolerance, abnormal insulin release, and positive urine sugar. However, in a few patients with diabetes mellitus complicated by glomerulosclerosis, although the blood glucose has been elevated to meet the criteria for the diagnosis of diabetes mellitus, but due to the reduction of glomerular permeability, the sugar cannot be filtered through the glomerulus into the urine, and then the urine glucose test will be negative. When the urine glucose test is negative, it does not necessarily exclude diabetes. The diagnosis or exclusion of diabetes should be based on fasting glucose and glucose tolerance tests. If you have symptoms of suspected diabetes and the urine test is negative, you should not give up the test easily, and further blood glucose tests should be performed to confirm the diagnosis.