How do you know if you have ketones?
You can’t always tell by how you feel. The only way to know for sure is to check.
At home, you can check for ketones with urine test strips or a blood ketone meter. Soon, there will be another option: dual glucose ketone monitoring. This new type of wearable sensor will continuously track your glucose and ketone levels in the fluid under your skin.
Knowing when to check for ketones — and what your results mean — helps you recognize when your body isn’t getting enough insulin. It can also help you know when it’s time to act.
But people with type 1 diabetes (T1D) don’t always remember to check for ketones.
Diana Isaacs, PharmD, CDCES, an endocrine clinical pharmacist at the Cleveland Clinic who specializes in type 1 diabetes care, points out that people often skip testing for ketones. She emphasizes that checking for ketones and having a ketone action plan are important parts of staying safe with T1D.
Here, you’ll learn when and how to check for ketones, what your results mean, and when ketones may signal a more serious problem: diabetic ketoacidosis (DKA).
Knowing when to check for ketones with T1D can feel confusing, but it doesn’t have to be.
Here’s what to know.
High glucose can be a sign to check for ketones, but it’s not the only reason. Ketones can form whenever your body doesn’t have enough insulin. This can happen if you’re sick or stressed, or when there’s a problem with insulin delivery.
These real-life DKA stories provide valuable insights from both caregivers and people living with T1D. They show why it’s important to recognize the signs and symptoms of DKA — and know when to check for ketones.
Viral Shah, MD, an endocrinologist and Professor of Medicine at Indiana University School of Medicine, recommends checking for ketones when you:
You may also notice changes in how you feel when ketones are present.
Early signs of ketones may include:
As ketones continue to build up, symptoms can become more serious, and DKA can develop.
Watch for:
You may not notice these changes right away. That’s why it’s important to check for ketones if you think you may have them.
Plus, ketones and glucose don’t always go up and down at the same time. This means you can have ketones even when your glucose is in range.
A common mistake is waiting too long to check for ketones when glucose levels stay high or when you’re sick, says Sarah Kippenbrock Lyons, MD, pediatric endocrinologist and Director of Quality and Safety for Pediatric Diabetes and Endocrinology at Texas Children’s Hospital.
“It’s always better to know than not know,” she says.
You can check for ketones in three ways:
Each method works a little differently. Here are the basics:
*Abbott's Libre DUO 10 Day glucose ketone sensor, for people ages 2 and older, received FDA authorization in August 2026. It should be available in the U.S. soon. The system continuously checks ketone and glucose levels. It’s the same size and shape as the FreeStyle Libre 3 and is inserted the same way.
While each checking method checks for ketones, they work differently. Here’s what to know about each one.
How ketones move through your body
Fat breaks down into ketones → ketones travel in your blood → your kidneys filter them out → your body gets rid of them in your urine
🧪 Urine testing
Checks for a type of ketone called acetoacetate
Looks backward: Shows the urine ketones your body removed earlier
🩸 Blood testing
Checks for a type of ketone called beta-hydroxybutyrate (BHB)
More current: Shows your ketone levels right now
🔘 Dual glucose ketone monitoring
Checks for a type of ketone called beta-hydroxybutyrate (BHB)
Most current: Shows your ketone levels right now and how they change over time
Urine ketone testing measures acetoacetate, a type of ketone your body makes when it uses fat for energy. But urine testing has a delay, and ketones may already be building up in your body before they show up in your urine, explains Isaacs.
Ketones can also remain in your urine for a while, even after your body has gotten rid of them. Because of this, it can be hard to tell when ketones are starting or going away.
Blood ketone testing measures beta-hydroxybutyrate (BHB). It’s the main ketone that builds up in your blood during DKA.
Because blood testing measures ketones in your blood at the time you test, it gives you a more current picture of your ketone level. But it’s still a snapshot, meaning you only know your level at the moment you check.
Dual glucose ketone monitoring also measures BHB, the type of ketone that matters most. The difference is that it continuously checks ketone levels, so you can see how they change in real-time.
Think of it like the difference between a photo and a video. Urine testing gives you a picture of what happened earlier, while blood testing gives you a snapshot of what’s happening now. Dual glucose ketone monitoring is more like a video, showing how your ketone levels change over time.
If other testing methods give a more current picture, you might wonder why urine ketone testing has been common among people with T1D.
For many, it comes down to cost.
“Urine ketone testing has been the most affordable and widely used option in the U.S.,” says Dr. Shah, but it’s not as reliable as blood testing.
You’ve checked, but what do your results really mean? That depends on the type of method you used.
Urine tests use color changes to show a general range of ketone levels. Blood tests and continuous monitoring give you a specific number, while continuous monitoring also shows how your ketone levels go up and down in real time.
Here’s a quick look at the three ways to check for ketones, and what each one tells you.
Urine ketone test results aren’t as exact as blood tests, explains Isaacs. Results are based on color changes of the test strip, and are measured like this:
Blood ketone test results and dual glucose ketone monitoring are measured in millimoles per liter (mmol/L):
*Before using blood or urine ketone test strips, always check the expiration date, says Isaacs. Old strips might not give the right results.
Finding ketones doesn’t automatically mean you have DKA. It just means ketones are in your body.
You can have ketones for different reasons. These include not eating for a while (fasting), exercising, or being sick.
DKA is different. It happens when there isn’t enough insulin, so ketones keep building up. This makes your blood too acidic. DKA is very serious and can be life-threatening.
Dr. Lyons explains, “High ketones can occur without high glucose in the setting of illness.” That’s why it’s important to check for ketones even if your glucose is in range.
Finding out you have ketones doesn’t always mean you need emergency care. But it does mean you need to pay attention.
Checking your ketone level is just the first step. What you do next depends on your results, glucose levels, symptoms, and ketone action plan.
In Part 3, we’ll talk about what to do if you have ketones. You’ll learn how to use your ketone action plan, when and how often to check again, and when to call your care team or seek emergency help.
Medical Disclaimer: T1D Exchange does not provide medical advice. The information in this article is for educational and informational purposes only and is not intended to replace guidance from your healthcare provider. If you have questions or concerns about your health, treatment, or diabetes management, please talk with your healthcare provider.