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What do I believe

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Meter accuracy is not a new issue.

As I wrote in a post on my other blog back in May, usually my meter and my CGM match up close enough that I don’t spend too much time thinking about the results. That day however, I had results that were 100 points different from each other within one minute. Three test strips, one DexCom, and I still had no idea what number to believe.


At Friends for Life, I received a coupon for a free meter from Nova. When I first started pumping in 2004, Nova was the brand that was linked to the MiniMed pump, but I remember nothing but accuracy issues from that time. I trusted OneTouch and doubted Nova. Now I’m not sure who to believe.

The new Nova meter came with 10 strips which I used to conduct a little experiment. I wish it wasn’t so difficult to get test strips because I’d love to try a few different meters at the same time, but not enough to pay out of pocket (at $1 a strip) for them.

The past two weeks or so, I use different situations (high, low, steady, dropping, etc) to see if I could find some sort of pattern (Kerri also recently checked out accuracy).

8-02 8:55 pm - 160s or higher?Nova and DexCom seem to agree, with One Touch significantly off.8-02 11:49 pm - somewhere around 150Nova seems a little lower than the other two (but without doing the math, I bet they are all within 20%).

8-04 8:42 pm - matching?We seem to all agree on this one. Time for a snack.8-06 7:50 pm - two hundred ??OneTouch loses again.8-08 7:51 pm - steady at what number?They all agree that it is time for a snack.8-08 10:53 pm - dropping againDifferent night, same snack.8-14 3:51 am - dropping but how far?Note the time on this one. Can I also point out that this is why I am frustrated.

A lot of the time they all agree, but then sometimes it’s a mess.8-13 11:38 10 pt difference. 8-14 12:28 29 pt differenceI had inserted a new DexCom sensor so I was waiting for it to warm up. Totally surprised by the results at 11:30. Then at 12:30, I was frustrated by the difference. How quickly was I dropping?
8-14 12:28 am - DexCom in warmup periodSince the OneTouch didn’t agree with itself (?!), I got out the other meter for a comparison. That is a pretty significant different when I am worried about dropping too quickly.8-14 1:05 am - DexCom in warmup periodSame night – at 1 am, another Nova comparison. Since I didn’t have a CGM ready as back-up I really wanted to know if I was still dropping before bed. I was, but by how much?


I have absolutely no idea what to do next. Other than put all my meters somewhere special.


11 responses

  1. I would like to put my meters someplace special also when stuff like that happens.

  2. So did One Touch answer your tweet? I’m curious! I think the meter companies are liable to provide accurate products but the FDA is just as liable to improve the current 20% accuracy standard. It’s all very bothersome. And you don’t really want to add more meters to your experiment unless you want to drive yourself crazy! 😉

  3. Here’s how I solve the problem: I have one and only one meter; it’s six years old. I’ve never had more than one since I got my first meter in 1978.
    The variance is simply an academic question in my case because I have locked on to a successful routine for so long and I rarely eat crazy stuff that I can pretty much tell you most of the time within 20 points what my BG is. (I do not use a CGM)
    Another distinction: I use my test results to confirm what I expect to be the case (and usually it does.) I don’t use the results as a starting point for management. There are surprises from time to time but it’s worked wonderfully well. So well that I have slept all night, every night since dx. It’s also why I have no complications or complaints or worries after 52 years as a T1.

  4. Stacy –

    The DM’d the phone number to their customer service line so that we could troubleshoot. I have not had a chance to do that yet. I haven’t done anything different, but maybe older meters become less accurate?

  5. Also on the way to work yesterday I was either 53 or 111. I will tell them where they can put their 20%

  6. Thanks, Sara, for posting this. For being the voice for this issue. I have called Lifescan so many times. Nothing changes. Same issues as you have. Somedays the #’s are in sync, other days 100 pts off. Yesterday I got “LOW” – something I’d never seen. And I was feeling just fine. I have hypo awareness so I questioned the “accuracy” of that strip. It was “100” – no “LOW”.

    Also, with the 50 strip containers, I notice as I get to the last 20 or so of the strips I get a lot of “Error 4s” (test strip errors). i was using one meter exclusively and C/S @ Lifescan said it could be the meter. Sent me another UltraSmart. Same issue occurs with the new meter. I think the exposure to the air after opening the vial repeatedly might alter the strips. Especially in the humid, rainy, summer weather.

  7. I am totally with you on this topic! It is beyond annoying! Its like trying to get to a destination without knowing where you are and with a freaking broken compass. On sorta the same topic–are controls even useful? (I honestly NEVER run controls–I don’t even have control solution, but does that make me part of my own problem?) I guess if the meter was really crap/trash then the controls would be the way to know–even back in the day when I did run controls I never had one be outside of the acceptable (and very freaking wide) limit.

  8. Seriously, this “standard” has been accepted by the FDA since the early 80’s… time for a little investment I think. Surely the funds exists since the market is only growing

  9. Sara you still have one more meter to try, unless you ate that coupon and I can hook you up with a few extra strips if necessary for a test.

  10. Good point! I need to finish sorting and unpacking my goodie bag 🙂

  11. This is so very frustrating. We have had a similar experience. I’m trying to use up some extra strips that we have, but unfortunately, they’ve just caused me stress. When numbers are in the 100s and 200s and the variances and significant and the “extra” meter is always higher. When the numbers are low, the gap is much more acceptable.

    This is complete garbage. The numbers on the extra meter would define Caleb with out of range numbers much more significantly than our regular meter. But which is right? I want the one in-range more often to be right and find myself believing that. But that’s totally backwards.

    It makes a difference. A big difference. Accuracy is of paramount importance.

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