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How much variance in meters is acceptable?

Discussion in 'Parents of Children with Type 1' started by buckmarko, May 24, 2012.

  1. buckmarko

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    We have been using the Accu-Chek aviva since dx in October. From my research, the meter is supposed to be pretty accurate. We started on the OmniPod today, and the readings are off by 15-20 points. At dinner the aviva says 130 and his Pod (Freestyle strips) says 115. (Lunch aviva was 171 and pod was 150). I was just curious to see the difference bt the meters, so I had him do both at the same time. 20 points seems to be like a big difference. Is it? Should I not worry about it? Just seems like if his numbers are lower, that's a big difference if his bs is 60 compared to 40.
    Thanks for any help.
     
  2. lgouldin

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    They say 20% is acceptable...ugh
     
  3. swellman

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    Yep, 20% so.

    10 points at 50
    20 points at 100
    40 points at 200
    60 points at 300
    etc.

    EDIT: 150 and 170 is not a large difference ... a 13% relative difference.

    EDIT2: ... and you are NOT using the Freestyle Lite strips with the OmniPod, correct? Because you can't.
     
    Last edited: May 24, 2012
  4. lgouldin

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    When I think about it, a 100 could be a 80 or a 120...and still be within the 20%:eek:
     
  5. cdninct

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    With 20% variation, wouldn't the acceptable range at 100 be 90-110? 20% overall, not 20% in each direction? I've never been sure...
     
  6. TheFormerLantusFiend

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    Unfortunately, it's 20% in each direction, not 20% overall that's allowed.
    So let's say the real blood sugar is x, the meter can read anywhere from 4x/5 to 6x/5.
    Say my blood sugar reading is 100. Then 4x/5<100 <6x/5. If 4x/5=100, my real blood sugar is 125. If 6x/5=100, my real blood sugar is 83 (and a third). Both are allowable.

    To make matters worse, the meters are only required to be within 20% at blood sugars above 75; below they only have to be within 15 points.

    To make matter even worse, they only have to be in that range 95% of the time- if 2 strips out of each canister give readings 100% off, they're still okay by the FDA.

    I have tested my blood sugar at the same time as a blood draw at most of my doctor visits. My blood sugar meter has been anywhere from 2% to about 35% off.
     
  7. swellman

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    I hesitate to post this but I posted a graph that, I THINK, showed BGs and the risk zones due to meter inaccuracies. I hope I'm not misremembering my own post but I will see if I can find it.

    It's below but I'm not sure how helpful it is other than understanding how they test meters.
     
    Last edited: May 24, 2012
  8. swellman

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    Look at your Test Strip Bottle ... Freestyle

    Acceptable Range for Test Solution

    Low: 40-70
    Normal: 83-125
    High: 248-372
     
  9. swellman

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  10. Debdebdebby13

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    We use the aviva as well and I've noticed it tends to run higher than any other meter brand that we've used on occasion. Like when we get the sample packs for other meters I'll test simultaneously and the Aviva is always higher.
     
  11. Mish

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    we've also demo'd aviva next to freestyle and find that freestyle is consistently lower. Given that we had a crap a1c the past few times, I'm beginning to believe that the actual BGs more closely line up to the aviva. Sadly, I just hate the aviva meter but I've also learned that a 65 on the freestyle, without any symptoms, probably is closer to an 75 or 80. So it's helped us to think about over reacting to those upper range lows .
     
  12. buckmarko

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    Swellman, yes it is Freestyle and not the Lite. I had one heck of a time with our mail order pharmacy to get the Rx right. They kept wanting to give us the lite. Although one of the reps we are working with is using the Lite, I believe. She basically said the only difference is the Freestyle has a code and the Lite doesn't. Hmmm.
    Mish, wouldn't the lower bg's result in a lower A1c? I'm still learning how all this works, so I'm not sure?
     
  13. Sarah Maddie's Mom

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    Nope. If bg is running 10% higher than the meter is reading, then you're going to be treating "lows" that aren't and failing to correct highs that are. So A1c would reasonably be higher than the meter average suggests.
     
  14. buckmarko

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    Sarah, that makes complete sense. Swellman thanks for the grid. I'm not exactly sure how to read it? :confused:I actually think it was the bottle of test strips that were sent with our OmniPod start up kit. The control was testing low. (Which, Abbott has changed btw, it is now 76-114) But, the control on the new test strips is reading normal (90). They (Our PDM and extra freestyle) still read about 10 pts below our aviva, but I feel more comfortable using it now. But we will absolutely go with how he feels as well. It is kind of scary when you think about the allowable 20%. Thanks everyone for your comments.
     
  15. Ali

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    The variance does not seem that big of a deal until you are looking at things like insulin on board.So a meter of 123 with IOB when I would expect to be back to a 90 or below (after a meal) means I might need some more insulin. Or the same scenario but with a reading of 83(and IOB) and I would be eating some sugar to keep from going low with IOB. Plus add in that most meters 25 percent of the time are not even that accurate. It just adds to the confusion. An as we all know the difference between a nice 85 and a 55 heading south is huge. Ali
     

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