What Are Ketones?

Medically Reviewed by Jabeen Begum, MD on November 28, 2023
7 min read

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 that 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.

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

You produce ketones 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.

Ketone production is the result of your liver turning fat into ketones and sending them into your bloodstream. Your muscles and other tissues can then use them for fuel. The breakdown of ketones is known as ketosis. Your body also will go into ketosis if you're not eating enough carbohydrates. 

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

You might need to test for ketones 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.

Frequent heavy drinking (alcohol use disorder) puts you at risk for a condition called alcoholic ketoacidosis. This happens when your body produces critically high ketone levels, usually after binge drinking and throwing up when you're not getting enough to eat. Alcoholic ketoacidosis is a medical emergency for which you should seek help right away.

If you live with diabetes, 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've missed an insulin injection.
  • You're pregnant
  • You're on your period.
  • You've had surgery.
  • You've been unable to eat.
  • Your insulin pump stops working.

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

  • Thirst 
  • Fruity-smelling breath
  • Frequent urination
  • Dry mouth or dehydration
  • Headache
  • Dry skin

Additional symptoms include:

If your blood sugar level is high or you're sick, check your ketone levels every 4 to 6 hours. If you are pregnant and have been diagnosed with gestational diabetes, test them every morning before you eat breakfast.

A ketone test uses a sample of either your pee or your blood. 

You can use several types of tests to check your ketone levels:

Urine tests

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 your doctor’s office.

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

  • Put the test strip 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 ketone test strip’s color against the chart that came with your kit. This will show you the ketone level.

Blood tests

You can also get this test at home or at your doctor's office. To take the blood sample, your 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:

  • Wash and dry your hands.
  • Insert one of the blood ketone test strips into the meter as directed.
  • Prick 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.

Breathalyzer test

This newer test uses a handheld gauge to identify acetone -- a kind of ketone -- on your breath. Breathalyzer tests aren't yet reliable enough to use if you're at risk for DKA.

The best test for you

Blood tests give accurate readings of your current ketone levels. They are less messy to use as well. But blood tests are more expensive than urine tests, require a machine meter to use, and your insurance may not cover them. 

You can buy urine ketone test strips without a prescription at a pharmacy or online. They are easy to carry with you. Ketones in urine show your levels from several hours ago, and your results may not be accurate if you are dehydrated. The chart that accompanies the test is not as precise as a blood test monitor. Individually wrapped urine test strips will stay accurate longer.

Your doctor can tell you the best test to use.

A urine test will show that you have:

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

Blood test results:

  • Less than 0.6 millimoles per liter (mmol/L) = normal
  • 0.6 to 1.5 mmol/L = slightly high

  • 1.6 to 2.9 mmol/L = moderately high

  • Higher than 3mmol/L = very high

Your ketone values can vary depending on the test you take. Also, the range of ketone levels, low, normal, and high, depends on the person. 

Keep track of your results

Write them down 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 ketone levels, which doctors call ketonemia, might mean you have DKA. Call your doctor or go to the emergency room right away if your ketone levels are very high.

If you don't already have a plan in place, call your doctor to find out how much insulin you need to treat high ketones and what foods you should eat or drink. 

If your test shows a trace amount of ketones, it may mean your levels are starting to build. 

What you can do 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.
  • Do not exercise if both your blood sugar and ketone levels test high.
  • Eat a carbohydrate -- raising your blood sugar can help lower your ketone levels.
  • Drink a carbohydrate-rich beverage like apple or orange juice.


You can make lifestyle changes to keep your ketone levels in a safe range.

  • Keep a food and insulin routine. Eat meals that keep your blood sugar levels in check. 
  • Understand your insulin pump, how it works, and what to do in case it fails.
  • Everyone is different, so know your own ketone levels and when you should test them.
  • Be ready to test in case you have signs of DKA.
  • Carry backup insulin to treat ketones in case of an emergency.
  • Always wear a medic alert ID so that people know you have diabetes and can act quickly. 

If you live with diabetes, be sure to take your insulin as directed and on a regular schedule. Sometimes your body just needs a bit of extra insulin to keep your blood sugar regulated. The events of everyday living -- an illness, injury, operation, your period or pregnancy -- can make your ketone levels rise. It's important to pay attention to what your body is telling you and to be ready and able to test and act quickly in the event your ketone levels are too high.

What do ketones do to your body?

Ketones are an energy source for your body when glucose is unavailable. This process is called ketosis. Ketosis is a regular bodily function that happens when you're asleep, fasting, exercising, or on a low-carbohydrate diet.

What does "high ketones" mean?

If your blood sugar spikes or you've had too much alcohol, it can cause your ketone levels to rise to dangerously high levels, a condition called ketoacidosis that is a medical emergency.

Can ketones mean diabetes?

People with type 1 diabetes are at higher risk of developing diabetes-related ketoacidosis (DKA), but people with type 2 can develop it too. Although it's rare, you can have high ketones or even ketoacidosis if you don't have diabetes.

What causes high ketones?

If you have diabetes, your ketones can build if you haven't taken an insulin dose or enough insulin. Your ketone levels can also rise if you're:

  • Sick
  • Pregnant
  • Injured or had surgery
  • On your period

What is the ketone test?

You can use a blood test or a urine test to check for ketones.

What happens if you test positive for ketones?

If your levels are moderate or high and you're not sure what to do, call your doctor or visit an emergency room. High ketones are life-threatening and need hospital treatment.

What is a normal ketone level?

A normal ketone level is unique to each person. A negative test is usually considered normal, but you can also have trace, small, or moderate amounts of ketones in your urine or blood. Talk to your doctor about what is considered normal for you.

What do high ketones in blood mean?

High ketones in your blood mean your blood is too acidic. This leads to ketoacidosis, a potentially life-threatening condition.