What Are Ketones and Their Tests?

A ketone test can warn you of a serious diabetes complication called diabetic ketoacidosis, or DKA.

An elevated level of this substance in your blood can mean you have very high blood sugar. Too many ketones can trigger DKA, which is a medical emergency.

Regular tests you take at home can spot when your ketone levels run too high. Then you can take insulin to lower your blood sugar level or get other treatments to prevent complications.

What Exactly Are Ketones?

Everyone has them, whether you have diabetes or not. Ketones are chemicals made in your liver.

You produce them when you don't have enough of the hormone insulin in your body to turn sugar (or “glucose”) into energy. You need another source, so your body uses fat instead.

Your liver turns this fat into ketones, a type of acid, and sends them into your bloodstream. Your muscles and other tissues can then use them for fuel.

For a person without diabetes, this process doesn’t become an issue. But when you have diabetes, things can run out of control and you build up too many ketones in your blood. If the level goes too high, it can become life-threatening.

Who Needs a Ketone Test?

You might need one if you have type 1 diabetes. In this type, your immune system attacks and destroys cells in your pancreas that make insulin. Without it, your blood sugar rises.

People with type 2 diabetes can also get high ketones, but it isn't as common as it is with type 1.

Tests can show you when your level gets high so you can treat it before you get sick.

When Should You Test?

Your doctor will probably tell you to test your ketones when:

  • Your blood sugar is higher than 250 milligrams/deciliter (mg/dl) for two days in a row
  • You're sick or you've been injured
  • You want to exercise and your blood sugar level is over 250 mg/dl
  • You're pregnant

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Symptoms

You should also take the test if you begin to experience some of the signs of DKA:

If your blood sugar level is high or you're sick, check your ketone levels every 4 to 6 hours. During pregnancy, test them every morning before you eat breakfast.

A ketone test uses a sample of either your pee or blood. Talk to your doctor about which is best for you.

Urine Test

You can buy this kind of test at your local drugstore and do it at home. Also, you can have one done while you’re at the doctor’s office.

To take it, pee into a clean container to get a sample and then do the following:

  • Put the strip from your test into the sample (or you can hold the test strip under your urine stream).
  • Shake the strip gently.
  • The strip will change color; the directions will tell you how long that takes.
  • Check the strip color against the chart that came with your test kit. This will show you the ketone level.

Blood Test

You can also take this test at home or at your doctor's office. To take the blood sample, the doctor will put a thin needle into a vein in your arm to pull out blood or prick a finger.

You can also use a home meter and blood test strips. Some blood glucose meters test for ketones, too.

To take this kind of test at home:

  • Insert one of the blood ketone test strips into the meter until it stops
  • Wash your hand with soap and water, and then dry it
  • Stick your finger using the lancing device
  • Place a drop of blood into the hole on the strip
  • Check the result, which will display on the meter

What Do My Results Mean?

A urine test will show that you have:

  • No ketones
  • Trace amounts of ketones
  • Moderate levels of ketones
  • Large amounts of ketones

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Blood test results:

  • Less than 0.6 = normal
  • 0.6 - 1.0 = slightly high
  • 1.0 - 3.0 = moderately high
  • Higher than 3.0 = very high

Write down your results on a chart or in a journal. Then you can track your levels over time.

Slightly high levels could mean that ketones have started to build up in your body. You might have missed an insulin shot. Take it as soon as you can and check again in a few hours.

Moderate to high levels mean you might have DKA. Call your doctor or go to the emergency room right away if they are very high.

What Happens Next?

Call your doctor to find out whether you need more insulin. She might tell you to go to the closest emergency room.

Also try these steps to bring down your ketone levels:

  • Drink extra water to flush them out of your body
  • Test your blood sugar every 3 to 4 hours
  • Don't exercise if you have high blood sugar and high ketones
WebMD Medical Reference Reviewed by William Blahd, MD on September 15, 2016

Sources

SOURCES:

American Association for Clinical Chemistry: "Blood Ketones."

American Diabetes Association: "Checking for Ketones." "DKA (Ketoacidosis) & Ketones."

Joslin Diabetes Center: "Ketone Testing: What You Need to Know."

Juvenile Diabetes Research Foundation: "Type 1 Diabetes Facts."

UpToDate: "Patient information: Self-blood glucose monitoring in diabetes mellitus (Beyond the Basics)."

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