Tuesday, June 19, 2012

Only as Good as our Meters . . . .

Meter accuracy is definitely a big concern of mine.  When I really stop to think about it, it’s pretty scary that the accuracy requirement for blood glucose meters is + / - 20%.  After all, it’s those numbers on my meter that guide my important diabetes treatment decisions.  They help decide how much insulin I should take.  They let me know if I’m okay for exercise or if I need a snack first.  They tell me if it’s safe to drift off to sleep.  We are all expected to hit our A1C goals, but how can we do that if we are basing treatments on incorrect information?

When I posted recently about my switch from Accu-Chek to OneTouch, Carol left a comment raising the question of accuracy.  Until that point, I hadn’t really thought too much about different levels of accuracy between the two meters but I was so glad she planted the thought in my head.   (And I feel silly that it hadn’t occurred to me . . . . . )  I decided to do some simultaneous testing with both meters to see how the numbers stacked up.  Here’s what I found:
OneTouch Accu-Chek
78 75
85 80
59 61
114 113
108 109
82 85
56 62
89 85
When I look at those numbers I have two thoughts.  #1 - WTF, how did I manage to have eight tests in a row with a number no higher than 114 / 113???  I can attest that my numbers don’t always run like this, and in the interest of full disclosure I offer this (not so) lovely number from Saturday as proof:

But I digress.  Thought #2 is that I’m glad to see the numbers on both meters are consistent with each other.  No, it doesn’t ensure that either meter is giving me accurate readings - they could both be off by 20%.  But the fact that they line up with each other does make me feel a little more confident in the results.

But honestly, I wish I could depend on my meter being closer to 100% accurate.


  1. It bothers me as well. i don't know why there isn't more of a push from medical professionals for better accuracy.

  2. You know what, I had no idea that meters could be off by as much as 20%. It would be nice if the doctors told us that when we were DX'd.

    You would think that they would want to make sure meters are more like 99% accurate especially when it plays a HUGE part in the diabetes care/management especially in young children.

    20% can be a lot if there is a low. Which now makes me worried (more worried) for my kid. He was only DX'd this past September. Sorry, I am still new at this. *sigh*

  3. I think these findings are important. True, they may both be off by 20%, but they're both consistent; so at least you know that your treatment of these numbers is consistent too, and you always do the same thing when you see 75 (whereas a 68-but-really-75 would trigger a different response than an 82-but-really-75).

    It's important to note that your numbers are in a good range, because that's in the "sweet spot" of the meter, and the 20% doesn't amount to as much. 20% of 75 is about 15 mg/dl. 20% of 400 is 80 mg/dl. Big difference! (I'm also not sure if the 20% is a total window, meaning your reading can be 10% above 10% below; or a tolerance, meaning your reading can be plus or minus 20%).

    Medtronic is no longer offering the OneTouch Ultralink; they now have the Bayer Contour Link on their US website. I just "pre-ordered" that meter (half the blood!) and it'll be interesting to see how the two compare.

  4. This is a great post and a very important issue. Being recently diagnosed, I've managed to somehow acquire numerous meters and by accident I found out about the 20% accuracy! I'll often test on a couple different meters to see the differences. Sometimes they are way off, but overall they are somewhat in range. I'm from Canada so its a little unnerving to see a 10 mmol/l on one meter and a 7 mmol/l on the other. Those numbers will drastically change whether or not I correct before a meal. When I get results like this, I will often go on how my body "feels"; which isn't an exact science either! This is definitely a frustrating issue, especially being new to all this!!!

  5. I have found that they always match for us...but only these two brands. If I try one touch and contour or freestyle it's a mess.

    Btw gawgus numbers!

  6. Sometimes it's worth doing two tests with your meter, one straight after the other. I did this recently after doubting the accuracy of mine. I'm in Australia, so I think in mmol, but I'll do the conversion - First reading was 9 mmol (162mg/dl) and the second was 15 mmol (270 mg/dl) - only seconds apart

    Check your meter often, I'd say.

  7. The whole accuracy issue annoys me SO much! I've seen a 59, 71, and 80 in quick succession. The people at One Touch insist that the 59 and 80 are still within +/- 20%, but I highly doubt that. Even when I calculate it, it's not within 20%!!!

    I've found that my One Touch and Freestyle meters are VERY far off sometimes and very close at others. My One Touch would say 80, and my Freestyle would say something in the 120's...go figure!

    The only thing I have to say about my meter is that SOMETIMES it can be normal, like when I go for my blood tests and my BG on the test and on my meter are within 5 mg/dl.


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