Ketone monitors, from finger-pricks to all-day sensors
On August 25, 2026, the FDA authorized the first wearable that tracks ketones around the clock, Abbott’s Libre Duo 10 Day. It isn’t on sale yet. The one continuous ketone sensor you can buy today, SiBio KS3, costs £74.99 for 14 days on Amazon UK, which is £162.92 a month.
This site gives general information, not medical advice. Talk to your doctor or diabetes team before changing how you monitor or treat any condition.
Four tests, three different ketones
A sensor and a blood meter read the same ketone, beta-hydroxybutyrate. A breath meter reads acetone and a urine strip reads acetoacetate, so their numbers can’t be converted into each other (Dhatariya, 2017). Of the ketone monitors and meters we follow, 6 are on sale today.
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Blood meter
Beta-hydroxybutyrate (BHB) from a drop of blood, in mmol/L. Each finger-prick.
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Breath meter
Acetone from your breath, in ppm. Each breath test.
No longer sold: Biosense. The company told users in Sep 2024 it had gone out of business.
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Urine strip
Acetoacetate from urine, read against a color scale. Each strip.
Our drawings of generic devices, not to scale. Abbott’s Lingo, sold in the US and UK, reads glucose only, so it isn’t on this table (why). Prices, apps and regulators for every one: the full comparison.
Two of the four tests read in mmol/L
A continuous sensor and a blood meter both give beta-hydroxybutyrate in millimoles per liter, the unit the NHS uses for its blood ketone levels. Libre Duo 10 Day’s urgent-high alarm goes off above 3.0 mmol/L. A breath meter’s ppm and a urine strip’s color don’t sit on this ruler.
If you have diabetes
For people with type 1 diabetes, ketones can signal diabetic ketoacidosis, which happens when a lack of insulin lets them build up in the blood (NHS). The NHS and the American Diabetes Association publish the levels at which to act, and a diabetes team’s own plan comes first.
Libre Duo 10 Day is the sensor built for this: it alarms when ketones pass 3.0 mmol/L. SiBio KS3 is sold for diet tracking, and SiBio says it isn’t meant for diagnosing, treating or monitoring disease.
What a month of readings costs
A sensor costs the same every month, however often you look at it: SiBio KS3 takes a reading every 5 minutes, 288 a day. Strips cost more the more you test. Change the tests a day on the receipt to see where they pass the sensor.
Many people with diabetes in the UK get blood ketone strips on prescription, which changes the sums completely.
A month of ketone readings
UK prices, checked September 28, 2026
- SiBio KS3 sensor£162.92 288 readings a day, whatever you choose
- FreeStyle Optium strips£167.23 meter not included
- Keto-Mojo strips£48.67 plus £48.00 for the meter
- Ketoscan Mini breath tests£7.91 plus £189.99 for the meter
The sensor costs the same as FreeStyle Optium strips at about 1.9 tests a day, and the same as Keto-Mojo strips at about 6.7.
Guides
- How continuous ketone monitors work
The enzyme, the filament and why a sensor can differ from a finger-prick.
- Sensor, blood, breath or urine
Four tests that read three different ketones, side by side.
- Ketone levels by source
The NHS, ADA and research ranges in mmol/L, on one chart.
- Type 1 diabetes and DKA
What official guidance and the new expert recommendations say.
- Tracking ketones on a keto diet
What research calls nutritional ketosis, and what each test costs.
- How accurate are they?
What the published studies found, with the numbers.
- Buying in the UK or the US
What you can get in each country today, and at what price.
- Questions and answers
Short answers on FDA status, UK sales, Lingo, costs and accuracy.