Ketone urine test: what the result means

Urine strips detect ketones released by the body. They can appear after prolonged fasting, vomiting, a very low-carbohydrate diet or strenuous illness. In someone with diabetes, ketones may reflect insufficient insulin and can progress to diabetic ketoacidosis. The strip gives a category such as negative, trace or higher rather than explaining the cause by itself. A result can also reflect what happened earlier because urine testing lags behind changes in the bloodstream.

Follow the kit instructions, check the expiry date and compare the strip with its colour guide within the stated time. Record the result, glucose reading, symptoms and recent food or illness. Drink fluids if you can and follow your diabetes sick-day plan. Do not use a urine result to change prescribed insulin without clinical advice. A clinician may recommend a blood ketone test when a faster or more precise result is needed.

Contact urgent medical services for moderate or high ketones with vomiting, abdominal pain, deep breathing, confusion, marked drowsiness or inability to drink. People with diabetes should seek prompt advice for ketones during illness or when glucose is high, following their personalised plan. A low or negative result does not explain urinary pain, fever or back pain; those symptoms may need assessment for a urinary infection or kidney infection.

Ask which ketone level should prompt a call, whether you need blood testing, how to manage medicines during illness and how often to repeat the test. Clarify where to obtain replacement strips and which symptoms mean you should attend emergency care.