Diabetes Urine Tests

Urine tests for diabetes look for ketones in the urine.

• Urine tests may be done in people with diabetes to evaluate severe hyperglycemia (severe high blood sugar) by looking for ketones in the urine.
• Ketones are a metabolic product produced when fat is metabolized. Ketones increase when there is insufficient insulin to use glucose for energy.
• Urine tests are also done to look for the presence of protein in the urine, which is a sign of kidney damage.
• Urine glucose measurements are less reliable than blood glucose measurements and are not used to diagnose diabetes or evaluate treatment for diabetes. They may be used for screening purposes.
• Testing for ketones is most common in people with type 1 diabetes.
• Both people with type 1 diabetes and type 2 diabetes typically have microalbumin testing.

Urine tests are tests performed in a clinical laboratory or at home using self-test kits and a sample of the patient's urine. Urine tests can be performed for a variety of reasons, but in people with diabetes, they are most commonly used to look for ketones or microalbumin (see below). Urine glucose (sugar) can also be measured, but this is less valuable than blood glucose levels for diagnosis and monitoring of diabetes, so this is not commonly done as a way to monitor blood glucose status.

This test detects the presence of ketones, which are byproducts of metabolism that form in the presence of severe hyperglycemia (elevated blood sugar). Ketones are formed from fat that is burned by the body when there is insufficient insulin to allow glucose to be used for fuel. When ketones build up to high levels, ketoacidosis (a serious and life-threatening condition) may occur.

Ketone testing can be performed both at home and in the clinical laboratory. Ketones can be detected by dipping a test strip into a sample of urine. A color change on the test strip signals the presence of ketones in the urine. Ketones occur most commonly in people with type 1 diabetes, but uncommonly, people with type 2 diabetes may test positive for ketones.

The microalbumin test detects microalbumin, a type of protein, in the urine. Protein is present in the urine when there is damage to the kidneys. Since the damage to blood vessels that occurs as a complication of diabetes can lead to kidney problems, the microalbumin test is done to check for damage to the kidneys over time.

While urine tests can show signs that may signal diabetes, such as elevated sugar or ketones, the diagnosis of diabetes is made on the basis of blood tests. Urine tests may be done in some cases as back-up testing or for screening to see if blood tests should be done, but the diagnosis of diabetes is made after blood glucose testing.

The ketone test is generally recommended for people with type 1 diabetes. Those with type 1 diabetes should test their urine for ketones when they are ill, especially if they have vomiting and nausea. Pregnant women with type 1 diabetes may also be advised to test their urine for ketones. Ketone testing is also done when the blood sugar is noted to be very high (over about 240 mg/dL). Your doctor can advise you specifically about recommended testing practices for your individual situation. Sometimes, people with type 2 diabetes may be advised to check their urine for ketones. Those with type 2 diabetes should discuss with their doctor whether ketone testing is necessary and under what circumstances.

The microalbumin test is done once per year starting at the time of diagnosis in people with type 2 diabetes. Even though protein in the urine is a sign of long-term damage to the kidneys, many people have type 2 diabetes without knowing it, so it is unclear how long they have had the condition. In people with type 1 diabetes, the microalbumin test may not be performed until the condition has been present for up to 5 years.