Ketones are usually absent in urine. Their presence most likely indicates that the body is using fats rather than carbohydrates for energy. High levels of ketones may be present in the urine of individuals with uncontrolled diabetes because the body's ability to metabolize carbohydrates is defective.
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. Electrolyte imbalance and dehydration may occur when ketones accumulate in the blood. If these conditions are not corrected by adjusting the dose of insulin, the patient may develop ketoacidosis and ultimately diabetic coma.
Low levels of ketones may also be detected in the urine 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 of carbohydrates or increased loss of carbohydrates.