New meter very different results to old meter

I looked up this meter and it is made in the USA. I have read the specifications for this device and nowhere (absolutely nowhere) does it give any indication of accuracy. There is no reference to any standards such as ISO, which European and UK meters are mandated to be compliant to. I did find a throwaway line where it does declare it to be Plasma calibrated hidden in the owner's booklet so it should track most modern meters being sold today, but there are no indications what level of certification it has been passed to or any FDA reference. Most meters that meet the ISO requirements here in the UK can be traced back to an actual test report that they submitted to get clearance to market in the UK or EU, but it is not declared on the website. They quote the FCC standard it meets but that's all it seems.

Even in the UK most meters will measure to +/- 15 % of true reading, so two meters on the same blood spot could be 30% different and still be considered to be accurate. So at 10 mmol/l you can expect the two results as reported to vary between 8.5 to 11.5 and be claimed to agree. Sorry, but that is a fact of life.

I have 2 meters myself, and they are currently varying by 2 mmol.l (UK) and that is pretty constant so if I do not see that I suspect a misread by one of them. You need to record both meter results and average them over about a month before comparing them to find out what the offset might be. It becomes difficult where I am getting near hypoland, and I get one meter saying I am safe to drive my car, and the other telling me to seek assistance. I am hypo aware, so I then resort to how I feel, and munch a snack to make sure.

Edited to put units into UK not USA

Edited to correct a numeracy error

Do you mean glucorx mini? I have been using one for about 3 years, I am hoping to change when I get though all the strips I have. I been having trouble with the software. Downloaded about 50 readings
And got different results like years 2012 2015 2020 2026 2045 and say 23/11/12, 23/11/2026 so on all in year 2020. Also after the 1000 reading instead of dropping reading from 1 it drops from about 9050 it makes look for patterns difficult. As comparison of two meters can not help you. One thing I do if I get a reading iam not expecting is re test after rinsing my finger

woollygal said:

I’m type 2 not 1 and not I salon it’s more about diet management. It’s just got harder because I have no idea which one to trust.
According to new machine my body hates what I’m eating but ils machine is happy with it

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Auto correct?

The only way to be sure is to test several times against a clinical one,
They are built to a higher standard and regularly calibrated.

Note that I am an ideas person and leave the implementation to others!

I suspect that no two meters will give identical readings and that we just have to adapt to a new meter because although it may not give quite the same readings the overall trend will be much the same. In other words agonising over a 10% difference in the readings is probably counter productive.

woollygal said:

I’m type 2 not 1 and not I salon it’s more about diet management. It’s just got harder because I have no idea which one to trust.
According to new machine my body hates what I’m eating but ils machine is happy with it

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In the days before you had the new meter, you based your decisions on the old one, and it served you well. You can compare it to the Lab values taken with the HbA1c blood to see if it is actually high or low, by taking a reading in the surgery at the same time. Or by averaging the values for a month or so and comparing the average against the HbA1c.

Now you have a new kid on the block. If you are thinking of returning it as useless then stick with your old meter, else you are going to have to switch to it as the new yardstick, and adjust accordingly, If it is not being used for hypo detection, or medication change, or DVLA requirements, then it all becomes relative, and tightening up on your diet is probably not a bad idea anyway. It becomes less important when compared to the other uses for a meter.

In any case, a single spot reading is not useful on its own, I repeat suspect meal choices on another occasion to confirm since spot readings are affected by so many other influences that they are only a rough guide at the best of times. Secondly, I try to base my decisions on how the readings are trending, and I average on a daily basis which on an OMAD regime is effectively both the FBG indicator and the meal indicator. It is the changes you are needing to concentrate on.

I have been using 2 meters on the same drop of blood for 6 years now, and my SD Codefree has never been close to or below any other meter I have compared it to. If the difference exceeds 2 mmol/l then one of the meters is lying and I retest.

One other thing is that different manufacturers use different chemistries in their strips, and these can differ due to differing sensitivities to blood composition. For example, most meters are affected by the hematocrit value of the blood sample, and some meters get confused over sugar alcohols like Malitol or Sorbitol. This may be an explanation if you are using readymeals or low fat products.

Whilst I get what you are saying if you are stuck with the new one surely it’s the increase that matters more than the actual numbers for meal/food testing?

Oldvatr said:

Even in the UK most meters will measure to +/- 15 % of true reading, so two meters on the same blood spot could be 30% different and still be considered to be accurate. So at 10 mmol/l you can expect the two results as reported to vary between 7 and 13 and be claimed to agree.

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I agree about the +/- 15% but just to be pedantic about the maths. If the true reading is 10 then a meter reading 15% low would show 8.5 and a meter reading 15% high would show 11.5

Mr_Pot said:

I agree about the +/- 15% but just to be pedantic about the maths. If the true reading is 10 then a meter reading 15% low would show 8.5 and a meter reading 15% high would show 11.5

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To be even more pedantic, that is for one meter on its own. When comparing two meters back to back the error can be twice in worst case.

Oldvatr said:

To be even more pedantic, that is for one meter on its own. When comparing two meters back to back the error can be twice in worst case.

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It doesn't matter how many meters there are if they are all +/-15% accurate then the maximum range will be 8.5 to 11.5 for a true 10.

Mr_Pot said:

It doesn't matter how many meters there are if they are all +/-15% accurate then the maximum range will be 8.5 to 11.5 for a true 10.

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Each will be within their range (hopefully) but the difference between what they report will be twice One can report 15% high, the other be 15% low, so 30% difference. Remember that none of us knows what the true reading should be. Even a mass spectrometer analysis would have an error budget, The YSI blood analyser used in the lab is only 5% accurate.

However I was incorrect to show the range of readings to be +/- 30% and you are correct that they will be somewhere within the range you stated, but may disagree by the 30% I stated Since this is what we 'see' and not the true value, all we can hope for is that it lies in between the two. This is why the test solutions supplied have such a wide range of acceptable values.

woollygal said:

So just before Xmas my surgery changed my testing meter, i went from Gluco Rex mini to the true metrix air.
The new one is very swanky, has an app and Bluetooth and all sorts. But I am getting wildly different test results.
As an example tonight my old meter was 7.5, same finger new machine 10.8. Some have been very similar and I think once I even got the same. But I have no idea how to manage this.
So with tonight’s results my food was fine on old machine on new one it’s way too high,
Overall the new machine tends to be higher.

It’s making testing a mockery because what is the point in testing if the results can’t be trusted. How can I monitor food and the effect it has on me and try and control my diabetes if the blooming machines are all over the place.

is this normal? Do I need to go back to the drs? Seems a bit silly and trivial to bother the surgery when there is so much other important stuff going on at the mo.

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Hi,

All I know is my meter reads consistently in the region of 15% higher than the standard NHS issue used on me prior to my anti-VEGF jabs by the nurse who would test me with hers. Sometimes using my lancing device because sometimes I got a nurse who didn't have a clue how to draw blood.

Now by the same coincidence the app I use to log my BGs calculates HbA1c based on my logged BGs?
That also works out 15% higher than the figure coming back from the lab..

It may be worth while getting a "control solution" & checking it's calibrated correctly?

Hope this helps.

I believe you need to know how much a meal elevated your readings - so are those results what you would expect? If you eat a 'normal' meal, do you see the same increase in BG with the new meter?

woollygal said:

It was that one yes. Sorry phone changed it.
I understand about errors but how on earth do I manage my sugars if the new one is consistently higher. although today after exercising they were pretty much the same. New was 12.2 old was 12.0.
So which one do I believe and work with?
I understand about cleaning hands but this was same finger straight after the other. More often than not it’s the same prick of blood.

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The lower the number the more accurate they should be ... you manage you bg both by the meter and how you feel.. because who says the new meter is wrong and not the old one??

So you pick one stick with it.. if you get the the point of having a hypo with a bg of 5 then there is a fault with the meter.. if however you are OK its probably not too far off

At the end of the day you are never going to get lab results from a home meter.. the are simply to give an idea of what going on to help you manage

If you start obsessing you'll star heading down a slippery slope.. I have over 30 meters here and almost none agree with each other

You other option is to simply obtain a better quality meter the has been proven to conform to all the required standards like the contour next one.. but you'll pay more for strios

Umm. All three meters I've been given came with test control solutions. This is a little bottle with the fluid inside at a standard concentration of glucose. If you use the same fluid and both meters, then the meter that comes closest to the actual concentration is more accurate. That test time anyway.

If you don't have test solutions, then you can ask at your next diabetes appointment.

Unless you're having lots of hypos though, it's the trends that matter far more than getting an extremely accurate number.

Bug bear of mine that nobody produces a test solution that is exactly say 6 mmol/L.
That way you could test the accuracy of your meter anytime.
Have it in a small bottle like vape juice.

Perhaps evaporation or sunlight might effect the efficacy of the solution but in my head it should exist.

Ronancastled said:

Bug bear of mine that nobody produces a test solution that is exactly say 6 mmol/L.
That way you could test the accuracy of your meter anytime.
Have it in a small bottle like vape juice.

Perhaps evaporation or sunlight might effect the efficacy of the solution but in my head it should exist.

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No doubt the control solution is a fixed concentration, the range represents the allowed accuracy of the meter. If the solution was marked at say 6.0 mmol/L then the manufacturers would be inundated with complaints if readings weren't exactly 6.0. It is the strips, not the actual meter, that limit accuracy so there could be a change with every strip, certainly with every batch.