Can diabetes be diagnosed through a urine test?

While urine tests were historically the primary way to detect diabetes, they are no longer used to make an official diagnosis. Blood tests (like the A1C or fasting glucose) are far more accurate and are the medical standard. Your kidneys typically filter glucose, keeping it out of your urine entirely; sugar only spills into the urine when blood sugar levels become excessively high (usually over 180 mg/dL). Today, urine tests are primarily used to check for two things: the presence of ketones (which can indicate a dangerous complication called Diabetic Ketoacidosis) and microalbumin (a protein that serves as an early warning sign of diabetes-related kidney damage).