Ketone levels explained

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.

Ketone levels are given in millimoles per liter (mmol/L, sometimes written mM) of beta-hydroxybutyrate. Different organizations publish different cut-offs for different purposes. Here they are exactly as each source gives them.

For people with type 1 diabetes, and others at risk of diabetic ketoacidosis (DKA), ketone levels are a medical matter. Follow the plan from your diabetes team and the guidance from the NHS or the American Diabetes Association. No consumer ketone sensor replaces the testing your care team asks for.

NHS guidance for people with diabetes (blood ketones)

Blood ketones	What the NHS says it means
Under 0.6 mmol/L	Normal
0.6 to 1.5 mmol/L	Slightly high: test again in 2 hours
1.6 to 3 mmol/L	At risk of DKA: contact the diabetes team
Over 3 mmol/L	High: may be DKA. The NHS says to call 999 or go to A&E

Source: NHS: diabetic ketoacidosis.

American Diabetes Association

The ADA says that if blood ketones are 1.6 mmol/L or higher, a person with diabetes should get emergency medical care straight away (ADA).

Research definitions

Level	Definition	Source
Up to 0.25 mmol/L	Commonly found after an overnight fast	Dhatariya, 2017
0.5 mmol/L or less	Normal	Huang et al.
Over 1.0 mmol/L	Hyperketonemia
Over 3.0 mmol/L	Ketoacidosis range
0.5 mmol/L or more	Nutritional ketosis (study definition)	Tangney et al., 2020
0.5 to 5.0 mmol/L	Nutritional ketosis (review definition)	Fante et al., 2025

Nutritional ketosis ranges come from diet research and describe people without diabetes following a ketogenic diet. They are not DKA thresholds, and DKA is diagnosed by doctors from ketones together with blood glucose and blood acidity (Lancet Diabetes & Endocrinology).

How continuous sensors use these levels

International expert recommendations for CKMs (Lancet Diabetes & Endocrinology) set out four bands, normal, elevated, high and urgent high, with an alarm when ketones go above an “urgent high” level of 3.0 mmol/L (summary, paper).
Abbott’s Libre Duo has an Urgent High Ketones alarm above 3.0 mmol/L (Abbott).
SiBio’s app has adjustable high and low ketone alerts (Amazon UK listing).

Breath and urine units

Breath meters report acetone in ppm and urine strips use a color scale for acetoacetate. Neither converts directly to blood mmol/L. Why the tests differ.