The body normally metabolizes fats to carbon dioxide and water. Inadequate carbohydrate in the diet or defects in carbohydrate metabolism or absorption cause the body to metabolize fatty acids. Ketones (acetoacetic acid, acetone, and beta-hydroxybutyric acid) are produced during fat metabolism and are excreted in urine. Patients with untreated or inadequately treated diabetes mellitus are unable to efficiently utilize glucose due to insufficient insulin. Under these conditions, large amounts of fatty acids are metabolized, and abnormal amounts of ketones are excreted in the urine (ketonuria).