Ketones (or ketone bodies) are molecules the body produces when it burns fat instead of glucose for energy. Measuring blood ketones is useful both in diabetes and on the ketogenic (keto) diet. Here we explain which levels are normal and how to monitor them at home.
What are ketones and why measure them?
When little glucose is available (fasting, prolonged exercise or a low-carbohydrate diet), the liver turns fat into ketones. The main one measured in blood is beta-hydroxybutyrate (β-ketone). Monitoring it serves two very different purposes:
- In diabetes: a high level can warn of ketoacidosis, a medical emergency.
- On a keto diet: it confirms that you have entered ketosis and that the diet is working.
Normal blood ketone levels
| β-ketone level (mmol/L) | Interpretation |
|---|---|
| Below 0.6 | Normal |
| 0.6 – 1.5 | Light ketosis (common on a keto diet) |
| 1.5 – 3.0 | Marked ketosis; in diabetes, monitor closely |
| Above 3.0 | Risk of ketoacidosis: seek medical advice |
These ranges are indicative. If you have diabetes, any doubt should be discussed with your medical team.
Ketones and the ketogenic diet
On keto, the aim is usually to stay in nutritional ketosis (approx. 0.5–3.0 mmol/L). Blood measurement is the most accurate method, far more reliable than urine strips, which lose accuracy after the first few weeks.
How to measure ketones at home
With a 2-in-1 meter such as the CareSens Dual and some KetoSens strips, the process is simple and the result takes 8 seconds. We explain it in detail in our guide on how to use the CareSens Dual meter.
Frequently asked questions
Is it better to measure ketones in blood or urine?
In blood. It is more accurate and reflects your current level; urine strips lose reliability over time.
What level of ketosis should I aim for on keto?
So-called nutritional ketosis usually sits between 0.5 and 3.0 mmol/L.
When is it dangerous?
In people with diabetes, values above 3.0 mmol/L may indicate ketoacidosis and require medical attention.
This content is informational and does not replace medical advice. If you have any concerns about your health, consult a professional.