Laura Dolson is a health and food writer who develops low-carb and gluten-free recipes for home cooks.

Ana Maria Kausel, MD, is double board-certified in internal medicine and endocrinology/diabetes and metabolism. She works in private practice and is affiliated with Mount Sinai St. Luke's/Mount Sinai West.

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.

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:

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:

People with diabetes test for ketones to look for signs of diabetic ketoacidosis. If you have diabetes, you should test for ketones when:

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.

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:

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.

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 occurs when blood sugar and ketone levels are high. This increases 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.

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.

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.

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.

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.

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.

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.

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U.S. Food & Drug Administration. How to Safely Use Glucose Meters and Test Strips for Diabetes.

American Diabetes Association. DKA (Ketoacidosis) & Ketones.

United Kingdom National Health Service. Diabetic Ketoacidosis.

Gershuni VM, Yan SL, Medici V. Nutritional Ketosis for Weight Management and Reversal of Metabolic Syndrome. Curr Nutr Rep. 2018;7(3):97-106. doi:10.1007/s13668-018-0235-0

Goffinet L, Barrea T, Beauloye V, Lysy PA. Blood versus urine ketone monitoring in a pediatric cohort of patients with type 1 diabetes: a crossover study. Ther Adv Endocrinol Metab. 2017;8(1-2):3-13. doi:10.1177/2042018816681706

American Diabetes Association. Five things to know about ketones.

Crosby L, Davis B, Joshi S, et al. Ketogenic diets and chronic disease: weighing the benefits against the risks. Front Nutr. 2021;8:702802. doi:10.3389/fnut.2021.702802

Klocker AA, Phelan H, Twigg SM, et al. Blood β-hydroxybutyrate vs. urine acetoacetate testing for the prevention and management of ketoacidosis in Type 1 diabetes: a systematic review. Diabet Med. 2013;30(7):818-24. doi:10.1111/dme.12136

Misra S, Oliver N. Utility of ketone measurement in the prevention, diagnosis and management of diabetic ketoacidosis. Diabet Med. 2015;32(1):14-23. doi:10.1111/dme.12604

Paoli, A., Rubini, A., Volek, J. et al. Beyond weight loss: A review of the therapeutic uses of very-low-carbohydrate (ketogenic) diets. Eur J Clin Nutr. 2013;67:789–796. doi:10.1038/ejcn.2013.116

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