Ketone bodies are usually absent in urine. High levels of ketones are present in the urine of individuals with uncontrolled diabetes. In diabetes the ketones are present because the body's ability to metabolize carbohydrates is defective.

Detecting the presence of ketones in the urine is a valuable aid to managing and monitoring individuals with diabetes mellitus. Ketonuria is an indication that the insulin dose needs to be increased. It is also an early indicator of insulin dosage problems in juvenile diabetes or in diabetics experiencing other medical problems.

Electrolyte imbalance and dehydration occur when ketones accumulate in the blood. If these conditions are not corrected, the patient may develop acidosis and ultimately diabetic coma.

Low levels may be detected during conditions of physiological stress such as fasting, rapid weight loss, frequent strenuous exercise or prolonged vomiting. The presence of ketones in these situations is due to either inadequate intake or increased loss of carbohydrates.