Ketone bodies are intermediate products of fat metabolism, signifying active fat decomposition but incomplete oxidation, and urinary ketone bodies are negative in normal individuals. Positive urinary ketone bodies can be seen in several situations: first, it can be seen in certain normal people with fasting, chronic starvation, and excessive dieting, where the energy supplying substance in the body is fat, which can appear in the urine as ketonuria due to incomplete oxidation into ketone bodies. Secondly, it can be seen in patients with liver diseases, such as hepatitis and cirrhosis. The liver is the main site of sugar metabolism, and in liver diseases, there can be impaired sugar metabolism and insufficient gluconeogenesis, and fat can produce a large amount of ketone bodies to participate in energy supply. Positive urinary ketone bodies are most commonly seen in diabetes mellitus, where fat is the main energy donor, and this indicator is more pronounced when combined with ketoacidosis.