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Test Meters Don't Agree.

Discussion in 'Blood Glucose Monitoring' started by LordGrep, Apr 10, 2020.

  1. LordGrep

    LordGrep · Newbie

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    Before I go on I think I should just say "hello", and apologies for any rules I inadvertently break. If I have posted this in the wrong place, I'm very sorry, this place just seemed like the best place to ask this question.

    I am new to being diabetic. Got a type 1 diagnosis about 4 weeks ago, and things have been interesting. I can't believe just how well I feel, it's amazing.

    Ok.. So ...Here's my question to all you good, knowledgable, and wise folk:

    In hospital, after an amazing consultant finally chilled out after spending 3 days getting increasingly more serious and worried, I was given a meter that did both blood sugar, and ketones. I have been dealing with little pricks ever since, and life was good. Been dutifully adding my numbers to a spreadsheet, and keeping track of all the things. No drama at all.

    A couple of weeks ago I decided to make a little going out kit (not that I'll be doing much 'going out' any time soon), and as my meter is a little big (I mean it's not 'that' big) I bought another meter from the same company [as the meter I have] this meter just did glucose, and it really is compact. Perfect!!

    I was just messing about with the new meter, and I took a test not 2 min after I did a test with the old one, and the numbers were off.. And I mean big time off. We are talking in the order of 40%. The old one is saying 6.1 and the new one 8.6. I have done all the verification steps with control solution (yeah I have gone this far with it).

    I have since done a lot of tests, and there doesn't seem to be a reliable difference, it fluctuates all the time, it's not like the new one is always 2mmpl higher, or a percentage higher. I mean it's off all the time, and randomly so.

    I took the step of emailing the company to ask them what gives, and I got a very strange reply. In essence, they said that "We don't recommend customers use different meters for this very reason", and that "The two meters are very different", and they wanted to talk to me on the phone about it.

    This had me thinking. Well the first thing I did was to ask nice Mr Google for some help, and he told me that the accuracy of the meters has to have at least a 12% accuracy. This confused me a bit more as these things go to the decimal point. Is the decimal number just there for show?

    The next thing that started to worry me was that one of these meters would allow me to get VERY low indeed and I would not know about it. I asked the company in the email "Which reading should I trust"? After all I am injecting myself based off these results, and I am getting worried that I might end up going hypo (not had one of those yet) and I wouldn't know about it, well I would get the symptoms, but I'd take a test, and think I was fine.

    So what do you think? Am I wrong to expect that a medical device should be accurate? How can something that is designed and sold for the same purpose give different results, and how is this something that should be accepted? After all they both are supposed to do the same job, give a readout of one's blood sugar.

    I have very deliberately not said what the meters are or the company I am dealing with as I haven't as yet talked to them and heard their explanation. The reason I am asking you good people first is so that when I do talk to them I am not going into the conversation dumb. Conceivably there might be a good reason that I am not aware of. If there isn't then I'd like to know that so that I don't just metaphorically sit there nodding like a dog when I could be asking more pointed questions.

    Thank you so very much from your help, and time,

    Grep
     
  2. searley

    searley Type 1 · Well-Known Member

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    Meter will never agree they are not lab grade so have a tolerance of 15%

    This is even seen on the test pots when doing a control test I have a Bayer pot here if I do I control test and get anywhere between 18 and 23 it’s considered correct

    The good news is that 15% of a smaller number is a smaller difference

    You could take the same meter and do a test 2 minutes apart and get quite different numbers

    Not to forget contaminants can have an effect washing hands some people use alcohol wipes which can effect numbers

    Meters are only intended as a guide on what you glucose is doing..

    Choose 1 meter and stick to it
     
    • Agree Agree x 1
  3. BaliRob

    BaliRob Type 2 · Well-Known Member

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    Not quite to the point but of interest I think - I used the same meter for 15 years - One Touch Ultra - which was the most CONSISTENT of all meters I used then or subsequently. J&J selfishly sold this part of their repertoire
    leaving ALL overseas COMPLETELY ABANDONED without notice. That is the reason for my posting I
    suppose.
     
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  4. Chas C

    Chas C Type 1 · Well-Known Member

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    Its already been mentioned that meters will always differ, its far better to not worry about comparing but if you do then wash hands first, prick chosen finger and use the same finger pin prick to feed blood both the meters test sticks (one after the other). Then at least then you know the tests should make or better the 15% range.
     
  5. LordGrep

    LordGrep · Newbie

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    The tests I have done were using the same blood from not just the same place, but the same blood sample. I don't use alcohol wipes, and my hands were washed first. The difference I am getting is huge, well over 15% as I mention above there has been a 40% difference between samples. And when one is saying 4, and the other 6 one is telling me I am fine, and the other is saying I am getting closer to being too low. Which do I believe?
     
  6. urbanracer

    urbanracer Type 1 · Moderator
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    Hi @LordGrep

    Your meter is just a collection of electronic components - it is simply measuring a resistance between 2 terminals. If the input was absolutely identical each time then it would always give the same output.

    Variability is introduced in the mass manufacture of test strips which contain enzymes that react with the glucose in your blood. A tiny change in the composition (or amount) of the enzymes is going to give you a different reading - hence home glucose measurement systems sold in the EU conform to ISO2013:2016 standard which provides an allowable tolerance range, you can read about that here, https://www.diabetes.co.uk/blood-glucose-meters/blood-glucose-meter-accuracy.html

    If you read that then you will have seen that if your true blood glucose level is above 5.6mmol/l, you enter the +/- 15% tolerance band. And so there is more than 1 way to look at your results.

    Let's suggest for a moment that your 'true' glucose level is 7mmol/l. Your tolerance band would then be +/- 1.05 (doing sums in my head only) meaning you could conceivably get readings between 6 to 8 mmol. So 1 meter could be high and the other low, your issue doesn't neccessarily point to a 40% error although you seem to be a little outside the 15% range. Arguably, this is covered by the requirement for results to be accurate 95% of the time, and therefore 5% is allowed to be outside of the range.

    General advice - stick to one meter, look for trends and don't get too hung up on individual readings. The meter which reads lower may be safer from the point of view of preventing hypos - and you will get a clearer idea of which 1 is correct when you have your a1c's done.
     
    • Agree Agree x 1
    #6 urbanracer, Apr 12, 2020 at 12:20 PM
    Last edited: Apr 13, 2020
  7. oldgreymare

    oldgreymare Type 1 · Well-Known Member

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    I also used OneTouch Ultra meters for over 10 years - at one point I had four of them. Definitely the most reliable with little variation (typically +/- 1 mmol or much less between them). Last summer my local endocrinology unit, OCDEM at the Churchill Oxford, started a survey comparing I think it was 8 different brands of meters. I had signed up for this, but then was unable to attend the DAFNE course so did not take part. But one of the diabetic nurses did comment during another appointment that it was shocking how much some of the meters seemed to vary. Not sure what happened with the results of this survey. Hopefully we can find out once the clinics can return to more normal conditions.
     
  8. aspot

    aspot · Member

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    Very interesting... I have currently 3 meters. Used Freestyle Optium Neo, then AccuChek Mobile and now Contour Next One. Prefer the last 2 as they comes with Bluetooth and work well on smartphone. Did some tests on all of them and as expected AccuChek Mobile was way off. The Contour and Freestyle were almost same (6.8 vs 7.1) but AccuChek 12.7. Spent one day testing all 3 devices and results were same. The AccuChek was always few numbers higher (3-5!). So after 12 tests I ruled out AccuChek (not going to use it anymore)despite being technically the best of all. Also did test when visiting my diabetes nurse and AccuChek "failed " again. The nurses meter showed 8.1,Freestyle 7.9 and AccuChek? 11.9!!!
    I'm not lobbying for particular brand, but accuracy is very important for me. It determine the insulin intake and if incorrect, we all know what can happen...
    I would say try your meter (s) when seeing your diabetes nurse and use the one closest to his/her reading.
     
  9. jjraak

    jjraak Type 2 · Well-Known Member

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    I'm with @urbanracer here.

    Just stick to one, get used to the trend, rather then get caught up in his accurate it is compared to xyz brand.

    Good luck on the journey.
     
  10. searley

    searley Type 1 · Well-Known Member

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    Trouble is who can say how accurate the consultants meter is?? At the end of the day they only use a meter and strips like us the only way to get a true result is a lab test... and even the meter that matches that now may not with the next pit of strips / weather change / humidity change / temperature change etc etc

    Accuracy for insulin is not such a valid reason because you get used to how much to take for what that particular meter reads

    I stick with 1 meter I know if it reads 11 that 3 units will bring me to where I need to be

    They work on a percentage of accuracy so the lower the number the closer to the actual value it will be

    Use 1 meter get used to it and don’t worry what other say or you’ll be checking and double checking the test if your life
     
  11. aspot

    aspot · Member

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    I agree. I like the Freestyle Optium Neo, because it also checks ketons and other advanced features. However the lack of Bluetooth and mobile/PC apps is a dealbreaker for me. Was never a fan of filling the book. Now deciding between AccuChek Mobile and Contour Next One. Like the AccuChek as it's very handy and no need for stripe, but accuracy is a big issue... As mentioned before the contour and Freestyle were very close in results and I don't want to inject extra insulin to go too low... the reason I am doing these "comparing tests " I want to be sure have the best possible device. Don't trust doctors (at some point) as they are "influenced " by suppliers. So for me now is to choose between AccuChek and contour...
    If anyone has experience with these two devices please share your experience... JPEG_20200602_230019_4392590554703915397.jpg JPEG_20200602_230034_2666867245844903661.jpg
     
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