Ketone body is a general term for acetoacetic acid, β-hydroxybutyric acid, and acetone, which are products of the fatty acid catabolism process. When glucose metabolism is impaired, fat catabolism is strengthened, so that ketone body production is increased, and when it exceeds the rate of utilization by extrahepatic tissues, the ketone bodies in the blood are increased and ketonemia is formed; excessive ketone bodies are discharged from the urine and ketonuria is formed. At present, in addition to the qualitative detection of urinary ketone bodies in the clinic, the quantitative detection of ketone body fractions in the blood directly by enzymatic methods. Urinary ketone body determination is often used nitrohydrocyanate test method, which can be reacted with the ketone body components of acetoacetic acid and acetone in the urine, so as to qualitatively determine the urinary ketone body. Normal urine is negative for urinary ketone bodies. Positive urinary ketone bodies, in patients with type 2 diabetes mellitus or undergoing treatment, suggests poor efficacy or important complications. Urinary ketone bodies (++) need to be combined with physical symptoms, as well as determining the cause of the positive ketone bodies, to determine whether hospitalization is necessary.