Ketone monitoring on ketogenic diets
Last checked September 28, 2026
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This site gives general information, not medical advice. Talk to your doctor or diabetes team before changing how you monitor or treat any condition.
People following ketogenic (very low carbohydrate) diets often measure ketones to see whether they are in ketosis. This page sets out the published definitions and the options, without judging any diet.
What research calls nutritional ketosis
- A 2020 study defined nutritional ketosis as blood BHB of 0.5 mmol/L or more (or urine acetoacetate of 15 mg/dL or more). In 19 women, blood BHB went from about 0.1 mmol/L to 0.6 to 0.8 mmol/L after 8 days on a modified ketogenic diet (Tangney et al., 2020).
- A 2025 review uses 0.5 to 5.0 mmol/L (Fante et al., 2025).
More ranges on the ketone levels page.
The options and what they cost
| Test | Example | Running cost |
|---|---|---|
| Continuous sensor | SiBio KS3 (sold for diet tracking, adults 18+) | £162.92 a month |
| Blood meter | Keto-Mojo GK+, 1 test a day | $25.85 a month |
| Breath meter | Ketoscan Mini, 1 test a day | £3.95 a month plus the meter |
| Urine strips | Ketostix, 1 a day | $7.60 a month |
Work out your own numbers with the cost calculator. Where to buy: SiBio KS3 on Amazon UK, SiBio shop, Keto-Mojo US, Keto-Mojo UK.
Things research has found
- Urine strips become less reliable the longer someone stays in ketosis, because the kidneys reabsorb more acetoacetate (Fante et al., 2025).
- Breath acetone is only moderately correlated with blood BHB (Fante et al., 2025).
- The first published test of a continuous ketone sensor was in 12 healthy people on low-carbohydrate diets, who wore sensors for 14 days (Alva et al., 2021).
- A 2026 study of SiBio’s KS1 found readings drifted down over 14 days (Kjær et al., 2026). More on accuracy.
The diet studies above were in people without diabetes. For people with diabetes, people who are pregnant, and people taking insulin or SGLT2 inhibitors, ketone levels carry medical meaning: Abbott lists people taking insulin or SGLT2 inhibitors among those at higher risk of raised ketones (Abbott). That makes ketone targets and diets a conversation for their doctor or diabetes team, not for a consumer sensor.
More guides
- How continuous ketone monitors work
- Sensor vs blood vs breath vs urine testing
- Ketone levels explained
- Ketone monitors, type 1 diabetes and DKA
- How accurate are ketone monitors?
- Buying in the UK vs the US
Sources
- Tangney et al., Current Developments in Nutrition, 2020: defining nutritional ketosis
- Fante et al., Frontiers in Nutrition, 2025: β-hydroxybutyrate testing
- Alva et al., J Diabetes Sci Technol, 2021: feasibility of a continuous ketone sensor
- Kjær et al., JMIR Diabetes, 2026: SiBio KS1 in a randomized trial
- Abbott press release on the FDA authorization, 25 Aug 2026