Which is the best ketone meter on the market?

Knowing your blood ketone levels can be powerful feedback. It’s objective. It’s motivating. And it is the kind of information that lets you know where you are and whether you need to make a change to reach your goals. Many people experience the most benefits when blood ketone levels get above about 1.5 mmol/L. Are you there yet? A ketone meter gives you this objective feedback as often as you decide to test.

If you are ready to invest in a blood ketone meter, which one should you buy? I wondered, too, so Diet Doctor bought the four most prominent meters available on Amazon (US), and I ran them through our testing protocol.

In this review, I compare them across three attributes: accuracy, price and simplicity.

Contents

1. The four brands of ketone meters
2. Accuracy
3. Price
4. Simplicity
5. Conclusion: The winner

The four brands

Here are the four contestants, and a picture of what you get when you unpack your kit:

CareTouch

Keto-Mojo

Nova Max Plus

Precision Xtra

As you can see, every meter I tested comes with a carrying case, a manual, 10 ketone strips, a lancing device (to help you get a small drop of blood as painlessly as possible) and disposable lancets (for a sterile finger-prick each time you test). This is everything you need to test your blood ketones 10 times; after that, you will need more ketone strips (pricey) and disposable lancets (very inexpensive).

Accuracy

In order to assess the accuracy of the ketone meters, I compared their readings to a commercial blood test for beta-hydroxybutyrate. I used lab results from Quest Diagnostics, a large and reliable clinical laboratory in the US, to benchmark the meters.

Procedure

My procedure was simple. After a fast of 12-14 hours, blood was drawn at Quest Diagnostics. Within 5 minutes, I took a ketone reading from blood obtained from a single finger prick on each of the four meters. After a couple of minutes, I took a second reading on each meter (with a fresh finger prick and test strip).

I repeated this procedure three times, on three separate dates. The repetitive design of the experiment allows us to evaluate the blood sugar meters several times (six readings in total for each meter), which gives us a better idea of overall meter performance rather than placing too much weight on one single reading. I chose to test when I was in full-blown ketosis, in moderate ketosis, and out of ketosis, so we can see if the meters perform accurately in different conditions.

A word about fasting: you do not have to be fasting to get an accurate blood ketone test. However, I wanted to minimize the chance that my ketone levels would change rapidly in the minutes between the blood draw at Quest and the subsequent ketone strip tests. The best way to minimize large ketone level fluctuations is to fast.

Results

The results are outlined below. On each test date, the meters with the meter readings closest to the Quest results are highlighted in orange.

Discussion

For each test, all of the meters gave reasonable readings and correctly identified whether I was churning out ketones (test #1), in moderate ketosis (test #2), or out of ketosis (test #3). Overall, the Precision Xtra was slightly more accurate than the other meters, but the difference is slight.

One thing most users look for, which is a little different than accuracy, is consistency. To evaluate consistency, I tried to measure whether the meter gave identical readings for two samples that were likely the same. I tested that by taking two readings, just minutes apart, looking for the same or very similar ketone levels on those two strips.

Overall, the meters were internally consistent. However, both the Precision Xtra and Keto-Mojo showed a wider difference (0.4-0.5 mmol/L) between the two test strips during the first test (when ketone levels were high). Note that in both cases, both readings on these meters showed that I was well into ketosis; there was just a bigger variation than expected. In contrast, during the second test, the Precision Xtra and Keto-Mojo each produced two identical readings on the two test strips. This may mean that the first test was an aberration, or it could simply be because the margin of error increases as ketone levels rise.

Simplicity

How easy is it to use these meters? Are some better designed than others? Here, I review matters related to the user experience.

Meter start-up

Each meter comes ready to use. None of them require special calibration before taking your first reading. The CareTouch and Keto-Mojo include a code on the test strip vial that you should confirm matches the code displayed on the meter when a test strip is inserted. If it does not display the correct code, there is a special, coded strip provided with each vial of test strips that should be inserted into the meter to change the code. Other than that, in each case, you simply insert the test strip to turn on the meter and put it into ketone-reading mode. After a few seconds, the meter display lets you know that it is ready for a drop of blood.

You do have to insert the batteries (provided) into the CareTouch meter, but this is very simple. All of the meters are battery operated and will require occasional battery changes.

Setting the time/date is optional, but is nice if you want to look back through past readings and review them with an accurate time/date stamp.

Meter design

The CareTouch and Keto-Mojo meters are very similar. They appear to be manufactured by the same company, but branded differently to create two separate products. They feel very comfortable in the hand. The display is backlit and it is very easy to read the large digital numbers. There is only one button, which turns the meter on and initiates a scroll, in one direction, through past readings. Both of these meters also feature a hands-free test strip “eject” lever on the side. It works, although I am not sure that it adds much.

The Nova Max meter has a smaller, darker display, but is still very readable. It has forward and back toggle buttons on the front to make it easier to review prior readings.

The Precision Xtra meter has a side button you can press for more light. The digital display is large and and easy to read. This meter also has forward and back toggle buttons on the front make it easier to review prior readings.

Ketone strips

The ketone strips for the CareTouch and Keto-Mojo meters are visually identical, and were my favorite strip—a little wider and sturdier—which makes them easier to insert into the meter. Test strips come in a re-sealable vial; once opened, strips should be used within six months.

The Nova Max strips are more flimsy. On three of the six times I tested, I had to pull out the Nova Max strip and reinsert it before the meter was ready to receive a blood sample. (Note that I did not waste any strips, but just had to reinsert them.) Test strips come in a re-sealable vial; once opened, strips should be used within three months.

The Precision Xtra strips are narrower, but still rigid enough to insert and create the connection needed to put the meter (automatically) into ketone reading mode. The Precision Xtra strips are the only ones that come individually wrapped. Although it is possible that this packaging means they remain accurate for a longer period, they are a little tricky to unwrap and thus it takes a little bit longer to test. On the flip side of this, if you want to carry your meter and one or two strips with you, the Precision Xtra will be more compact, as you will not need the cylindrical vial for the other brands’ test strips.

Cases

The case for the CareTouch meter is a semi-rigid black clamshell. I prefer this, as it is more attractive and all of the kit components seem to fit into it more easily. The rest of the meters come with fairly similar black soft-sided cases.

Lancing device and lancets

I preferred the identical lancing device that came with both the CareTouch and Keto-Mojo meters. It was easiest to use and felt well designed in my hand. That said, all of these lancing devices were functional; the Precision Xtra was the most difficult to operate.

Data

The CareTouch and Keto-Mojo meters have better built-in data features. Both store 1,000 readings in memory, and average ketone readings (for 7, 14, 21, 28, 60, and 90 day period) can be displayed. You can purchase, at additional cost, a strip port cable and software for downloading the meter readings to your computer. (This feature was not tested.)

The Nova Max stores 400 readings. Although it averages blood glucose readings, it does not average ketone readings. No data export is available.

The Precision Xtra stores 450 readings. Although it averages blood glucose levels, it does not average ketone readings. Data export may be available; the manual advises interested customers to contact customer service.

UPDATE: Keto-Mojo now offers a free custom app and $25 bluetooth connector for easy tracking.

Extras

All of these meters can also be used to measure blood glucose levels. Just purchase the glucose strips made for your meter to utilize this feature. In addition, each meter can be tested against control solutions (available for an additional fee).

Summary

The CareTouch and Keto-Mojo did best for simplicity. Here is a table that summarizes my rankings of the meters for each of the simplicity attributes:

Meter simplicity ranking (1 is most simple)