The purpose of this article is to teach individuals on a ketogenic diet how to measure their blood ketone and glucose levels. This process is by no means a requirement; however, individuals new to keto or beginners just starting their fitness journey may benefit from having concrete data. It is extremely easy to go over your carbohydrate limit while on keto, so knowing how your ketone levels fluctuate is a great way to gauge your personal carbohydrate tolerance.
How to use a blood glucose/ketone meter
If you are looking to obtain both of these variable, make sure to obtain a meter that will measure both ketones and glucose. Many meters that measure both will require separate testing strips. If you have a meter like this, please note the process is exactly the same for both you would just use the different corresponding strip.
1. Load the needle into whatever lancet device you are using and set aside.
- Please note that every device will be different, but for pens you will need to pull the bottom trigger (after you have loaded the needle) to ensure it is ready to go.
- Most lancet pens have a twist dial that will allow you to adjust for how much blood you want drawn.
2. Wash and dry hands
3. Remove a testing strip from the packaging and insert it into your meter.
4. Use an alcohol wipe to clean your finger and wait about 10-20 seconds for it to dry
5. Once your skin is dry, place the lancet pin on the side of your finger and press the button to draw blood.
- The sides of your fingers have the least amount of nerve ending and will therefore be the least painful, however if you find yourself having a difficult time obtaining blood from the side, you can use the center part of your finger tip
- A trick to getting more blood to the surface is gently roll the skin forward towards the needle entry point
6. Gently touch the test strip to the blood and make sure the entire well is full (the machine should tell you when this has happened).
7. Wait a few seconds for the results.
Ways to improve accuracy
1. Stay seated for at least 5 minutes before measure blood glucose and try to refrain from intense exercise beforehand.
2. Be sure to clean the skin thoroughly and allow for enough time to properly dry.
3. Know the best time to test your levels.
Interpreting your results
In general, a score of 0.5-3 mmmol/L indicates an individual is in a state of ketosis, however this number may fluctuate from person to person.
On average, fasting blood glucose should be <100 mg/Dl (<5.5 mmol/L). After food consumption, blood glucose will rise. This number should be <140 ( 7.8) mg/dL within 2 hours of eating.
Blood glucose is usually giving in either mg/dL or mmol/L. To convert between mg/dL to mmol/L you simply divide by 18. If you would like to convert in the opposite direction (mmol/L -> mg/dL) simply multiply by 18.
To get more insight behind measuring blood ketones, be sure to check out Ketogneic.com’s youtube where I go in depth on this process.
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4. Harvey, C., Schofield, G. M., & Williden, M. (2018). The use of nutritional supplements to induce ketosis and reduce symptoms associated with keto-induction: a narrative review. PeerJ, 6, e4488. doi:10.7717/peerj.4488Last Updated on
Chelsea Malone works as a researcher in the field of health and performance supplementation. She contributes science-based articles and information to Ketogenic.com. She received her Bachelor of Science in Biomedical Sciences from the University of Central Florida and her Master of Science in Medical Sciences from the University of South Florida. Her specialties are in biochemistry, immunology, and pathophysiology. In her free time, she enjoys cooking, traveling, hiking, and reading.