How accurate is accurate enough when it comes to blood glucose and blood ketone meters???

photo (2)After two weeks of working with my physician, the insurance company, and the pharmacy I received my new ketone meter in the mail. I was so excited to have a new tool to get numeric feedback instead of resorting to the color-guessing-game with urine ketone strips. For the first time in a few days I had a smooth night of blood sugars and I didn’t have to wake up in the middle of the night to check on it. I was so happy to wake up after a full nights rest to see this: (Yeah, that’s an 82!)

At 9pm after a weight training work out, I tested my new Precision Xtra meter and was shocked with the discrepancy in numbers between the new meter and my Dexcom. So I pulled out some other meters to find out which one was more accurate. After a lot of blood and some frustrated feelings this is what I found (213mg/dl, 168mg/dl, 180mg/dl, 240mg/dl):

IMG_6343 (2)

The Precision Xtra Meter did not come with calibration fluid but my old Nova Max Plus meter did, so I calibrated that one and it was working well. I also tested for urine ketones and the reading showed about 1.5mg/dl. Here are my blood ketone readings (<0.5mg/dl, 0.8mg/dl):

IMG_6347 (2)

*The Nova Max Plus meter reads low when you have less than 0.5mg/dl.

So after a series of comparisons and calibrations using different vials of test strips and double checking the expiration date. I decided to get rid of one meter that seemed to be the largest outlier. Naturally, it was the one that I had been using consistently for the past couple of weeks. This left me with these numbers (225mg/dl, 207mg/dl, 229mg/dl):

IMG_6349 (2)

Not happy, but somewhat satisfied in the end.

Well, it turns out that glucose meter accuracy is regulated by the FDA (Food and Drug Administration). “The ISO (International Organization for Standardization) standard requires that 95% of results within range or slightly elevated be within +/- 20% of the true value.” (Check out this article for an in depth comparison on meter brands: The blood glucose number(s) that I did this test with were by lack of definition “slightly elevated” and my readings with the greatest discrepancy were 70% off.

If we can make iphones so intricate and sturdy why does diabetes medical technology that human lives rely on look like the first generation ipod? Does anyone else see a disconnect here?

My other question is why are my ketones so low? My macronutrient intake at this point in the day was 50.8g protein, 18.0g carbs, and 133.9g fat. I was about to eat my last large meal of the day but now I was left at a loss of how much insulin to take. It is understandable that a glycogen release from my strength training work out could have caused the blood glucose spike to ‘who knows how high’. Although, I didn’t yet have insulin in my system to correct for that so I was assuming I should have still been producing adequate ketones.

I’m not going to pretend like this event wasn’t emotional for me. I’ve been working so diligently to try and balance my blood glucose levels through this type of food choice and I honestly thought I was on to something. I feel like all my data up to this point could have been so grossly inaccurate that it discredits itself. However, my friend Matt mentioned, “Your trend data is powerful regardless of the actual # on your CGM.” I suppose there is some truth to that. Thanks Matt.

So how do you move on from this?  I could have easily spent the rest of the night frustrated and fed up.  I chose to move on by being grateful for the diabetes technology that I have access to and reminding myself how impressed I am by the substantial technological improvements that have occurred throughout my lifetime. Remembering that I cannot judge my health on one number also seemed important to recovering my mindset. Either way I had an amazing day and a great night’s sleep. Things aren’t perfect but they are moving in the right direction and that is something to be happy about.

“Life is 10% what happens to you and 90% how you handle it.” – Charles Swindoll


4 thoughts on “How accurate is accurate enough when it comes to blood glucose and blood ketone meters???

  1. Hi Hannah – I like your blog. I understand your frustration with the various blood glucose meters and CGMs that we use ti treat our diabetes. On top of that we need to make critical dosing decisions with a potent hormone, insulin, based on meters that are allowed +/- 20% accuracy!

    I know we should be grateful for the tools we have (I am) but in this day and age of technological wonders, couldn’t we improve our meter accuracy a bit?

    In any case, I congratulate you on your active and vigilant stance taking care of your diabetes. Your future older self will be very grateful!

    Good luck with your blog and please stop by the TuDiabetes Flatliners group once in a while.


  2. Your trend data IS powerful, but using it to calculate corrections can ruin your day. Minimizing complications until the FDA approval of immune proofing beta cells and having a full healthy life in the meantime is a battle. Thanks for sharing your blog with Type 1 Diabetic Athletes on FB!!


  3. Hello Hannah! Just discovered your blog, very nice information here. I am also a type 1 diabetic on a ketogenic (zero carb) diet, and also a strength athlete/martial artist. Regarding your frustration with ketones, I also went through a period of testing my ketones, and found unexpected readings at various times. Generally, they were lower in the morning, higher in the afternoon. Sometimes they were also very low after strength training. After lots of research, and lots of speaking with other keto-ers (not necessarily type 1 diabetics), I learned that the ketones we measure in our blood do not necessarily represent the same amount produced by our liver, because the body uses ketones as fuel. So if for example I have a reading of 1.5, and then do some serious strength training, my body may use these ketones as fuel so my reading after the training may be low, even < 0.5. This has been also my experience (pretty much like glucose, where if used by the body as fuel then it is lowered in the bloodstream). So I stopped worrying about the exact number, and focused on how I feel. I believe that if your macros are at the right place and you eat the right way, then that number is just an indicator, nothing more. Much like the glucose released from our liver, which is different at various phases, in the same way the body produces ketones if and when it needs them, mainly for use by the brain (if this holds true, then this is why the readings are generally lower in the morning, because you spent the previous hours sleeping). Anyway, this is just my experience and research – keep up the good work with this blog!!!


    1. Thanks so much for your comment! So glad to know there are others out there that are having success with the same approach. I agree about ketone monitoring. I just think it’s a nice way to evaluate the transition into ketosis. Best of luck in the future!


Thanks for your insight!

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s