Blood ketone meters are devices that allow you to test for ketones circulating in your body. These are chemicals produced by the liver when the body needs to burn fat as fuel.
Everyone has ketones, and they’re normally not a health concern. But if you have diabetes, high ketone levels can cause diabetic ketoacidosis (DKA), a potentially life-threatening complication.
Monitoring your ketone levels with a blood ketone meter may be recommended, especially if you have type 1 diabetes. Ketone testing is particularly important during periods of illness.
You might also use a blood ketone meter if you’re following a ketogenic diet and want to ensure you’re in ketosis.
This article discusses the purpose of blood ketone testing and the different blood ketone meters available. It also explains the use of blood ketone test strips and tips for buying them.
Blood Ketone Meters for Testing at Home
To test the ketones in your blood, you will need a blood ketone meter and a kit that includes the lancet pen and ketone test strips. These meters also read blood glucose test strips. Results download to your computer.
Other brands and models may be available, including but not limited to:
- Precision Xtra: This meter from Abbott Diabetes Care can store up to 450 measurements and will display your blood glucose averages over different time periods. You need to enter a code to switch from glucose testing to ketone testing. Users seem happier with the Precision brand, and researchers find it to be the more accurate. The strips require 1.5 microliters of blood. It also features a backlit display.
- Nova Max Plus: This meter from Nova Biomedical is often provided free with the purchase of two boxes of test strips. You don’t have to enter a code to switch it from blood glucose to ketone testing; it does that automatically when you insert a ketone test strip. If you are using it primarily for blood glucose, it will remind you to test for ketones if your blood sugar level is 250 mg/dL or higher. The test strips for the Nova Max are less expensive but also flimsier and give more error messages, requiring retesting. The strips require less blood than the Precision strips, only 0.3 microliters.
Ketone Test Strips
You must purchase ketone test strips as glucose test strips won’t test for ketones. You will also need to use blood from your fingertip rather from an alternate site.
The strips are for one time use only. They can be the expensive part of testing, especially if they are not covered by your insurance.
Follow these tips and precautions when purchasing test strips:
- Be sure to get the correct test strips for the correct meter (they are not interchangeable).
- Pay attention to expiration dates on the strips, both when you receive your purchase and when you test your blood. Expired strips will not give accurate results.
- The Food and Drug Administration (FDA) warns against buying previously-owned test strips. While it may be legal, you risk getting a product that hasn’t been properly stored and could be expired.
- The FDA also warns against purchasing strips that have not been cleared by the agency for sale in the United States.
How to Test Your Blood for Ketones
- Load a needle into the lancet pen according to package directions.
- Wash your hands with soap and dry them well.
- Remove a test strip from the packaging and insert it into the meter.
- Place the lancet pen on the side of your fingertip and push the button.
- Gently squeeze your finger to get a drop of blood. You will need a large drop to load the strip properly. After you do it two or three times, you’ll get a sense of how much blood you need. With the Precision meter, you need a bigger drop of blood than when you are testing blood glucose (even using the same meter).
- Touch the end of the test strip to the drop of blood until it fills the little opening and the meter registers.
- Wait for the meter to give you a reading (just a few seconds).
- Record your results. Discard the test strip.
Ketone Testing in Diabetes
People with diabetes test for ketones to look for signs of diabetic ketoacidosis. If you have diabetes, you should test for ketones when:
- Your blood glucose is more than 240 mg/dl persistently, especially if you have symptoms of DKA. Most diabetics have glucose >240mg/dL frequently.
- You are feeling ill.
- You have signs of dehydration.
- Your blood sugar increased too much overnight.
Studies have found that blood ketone monitoring is effective in decreasing emergency room visits and hospitalizations. It also improves the time to recovery in people who develop diabetic ketoacidosis.
Blood Ketone Results for People With Diabetes
Learn how to read your blood ketone results and discuss with your healthcare provider at what level you need to call her, which will depend on individual factors. These are general guidelines:
- A level of 0.6 mmol/L up to 1.0 mmol/L is considered normal for most people with diabetes.
- A level between 1.0 and 1.5 mmol/L is usually considered the point at which you call your healthcare provider.
- A level between 1.5 and 2.9 mmol/L indicates a risk for ketoacidosis. You should call your healthcare provider immediately.
- A level over 3.0 mmol/L is a medical emergency. You need to go to the emergency room or call 911.
Ketone Testing for Ketogenic Diets
If you have normal blood glucose, your blood ketones may be the highest in the morning after your overnight fast. However, many people report that their ketones rise over the course of the day. If you want to track your blood ketones day-to-day, picking one time of day and sticking with it will give you the best comparison.
Some factors besides the overall diet which may cause fluctuations include exercise and consuming fats with medium-chain triglycerides, such as coconut oil or MCT oil. And, of course, eating something (usually high in carbs) that knocks you out of ketosis will cause your ketone level to plummet.
How to Interpret the Results for Ketogenic Diets
If you are new to ketogenic diets and have a goal of nutritional ketosis (often defined as between 0.5 and 3 mmol/L), know that it can take two to four weeks to get consistently into this range. It often takes a fair amount of tweaking to figure out what you can and can’t eat, even for people who are low-carb veterans.
The ketone meter was developed to alert people with insulin-dependent diabetes to the signs of dangerous diabetic ketoacidosis. However, if you do not have diabetes and are on a ketogenic diet, you are using it for a different reason entirely. In this case, high ketones are not a sign of high blood glucose, are not caused by protein breakdown, and are not toxic.
For detailed information about nutritional ketosis, check out the books by Jeff Volek and Stephen Phinney: The Art and Science of Low Carbohydrate Living and The Art and Science of Low Carbohydrate Performance.
Ketoacidosis vs. Ketosis
Ketoacidosis occurs when blood sugar and ketone levels are high. This the acidity of the blood and is a medical emergency.
Ketosis, on the other hand, simply means you have elevated ketones—but not so elevated that they are dangerous. This can happen overnight or when you’re dieting.
A Word From Verywell
If you have diabetes, taking your blood ketone levels can lower your risk of hospitalization and complications of diabetes such as ketoacidosis. Discuss home ketone testing with your healthcare provider. If you don’t have diabetes, you may not be familiar with using fingerstick home blood testing and you will need to learn how to do it correctly.
When buying an FDA-approved ketone meter, it comes down to individual choice and which you find easiest to use. Always follow the directions scrupulously and repeat the test if you think you have made an error, as it will affect the results.
Frequently Asked Questions
Are blood ketone meters more accurate than urine test strips?
Yes. In addition, research indicates that people find blood ketone meters more convenient and are more likely to test ketones with one than with urine ketone strips.
Does insurance cover blood ketone meters?
Possibly, but only if the ketone meter is medically necessary. Insurance is not likely to cover blood ketone meters for people who are testing to see if they are in dietary ketosis. However, people with diabetes who have a history of ketoacidosis may be able to make a case for coverage.
What should my blood ketones levels be in ketosis?
When using a blood ketone meter to monitor your ketone levels on the keto diet, nutritional ketosis is between 0.5 and 3 mmol/L. You are in ketosis if your ketone meter results are in that range.
Does drinking water reduce ketones?
Yes, drinking water can help to flush ketones from your body. For people with diabetes, this can help prevent diabetic ketoacidosis (DKA). In those following a keto diet for weight loss, this may help minimize diet-related side effects, such as bad breath.
How long can you safely stay in ketosis?
It is unclear how long you can safely stay in ketosis. A 2021 study found that following a ketogenic diet for extended periods can have negative health consequences, including increased bad cholesterol and risk of chronic kidney disease, cardiovascular disease, and more.