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3 DIFFERENT READINGS 3 DIFFERENT METERS 1 BLOOD SAMPLE

Debandez

Well-Known Member
I have been using a freestyle optium neo since dx. This week I received a free TEE2 i also bought a cholesterol testing kit which doubles up as glucose monitor. So this morning after my breakfast I tested one blood sample in each monitor. 3 different readings. The lowest being my original meter. So I'm sticking with this. 7.2 after 2 hours .. .after a.... bacon.... toastie!!! Extra thick slice too!!! I know I know....i had a weak moment as never touch bread. The TEE2 read 8.3 and easylife was 7.8.

How can they vary so much!!!
 

Even if you'd tested the same sample 3 times in the SAME meter, the readings could have varied just as much or even more. Though some meters are also known to be, on average, higher or lower than others. To make things even more confusing, some meters differ more from others when the true value is low or high.

A modern meter should be accurate to 15%. When small differences matter, that's a lot of inaccuracy. The only way to be absolutely sure of what your true level is, is to take several readings and average.

E.g. If your true level was 7.2, you could easily get an 8.3 on a modern meter.

Things get even worse when measuring before-and-after-food. If your before reading is much higher than 'truth', and your after reading is much lower than 'truth', you could think you've eaten a safe food, but it's actually not safe at all.
 
I found the same thing .. I bought an Accu-Chek Mobile when I started taking glucose readings in March .. Recently I decided to check ketone levels too , so I bought a Caresens Dual , which also takes glucose readings. I tried both on same blood sample and got glucose readings of 4.7 and 3.9 and incidentally 0.4 for ketone.
 

Something else to consider is different batches of strips. I had a batch last summer that consistently read higher as shown on my average blood sugar graph, the yellow circle. (Ignore the blue circle that was my foot op and steroid shot.)
 

I have to say congratulations on the overall downward trend, it's remarkable when you see it like that.
 
Many blood glucose meters measure glucose level of the whole blood, whilst some just report the glucose levels of plasma – the fluid part of the blood. You should check in the specifications for each meter. Older meters and some newer ones are not calibrated. (whole blood and plasma bloods are not the same thing). If one them is not calibrated to do the conversion, they will never read the same. Whole bloods are approximately 12% lower than plasma bloods.

My Accu-Chek Mobile and my Codefree both give plasma blood readings.
 

WOW you really do learn something every day! Brilliant. Thanks.
 
All home meters measure whole blood because that's what comes out of your finger. They then apply a correction so that the reading is an approximation of plasma glucose. This has been been the case for meters manufactured since 2010.
 
Mr_Pot said:
All home meters measure whole blood because that's what comes out of your finger. They then apply a correction so that the reading is an approximation of plasma glucose. This has been been the case for meters manufactured since 2010.
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Is that all meters manufactured since 2010? Is it a requirement for marketing? Are some not calibrated? I also read somewhere that some meters aren't calibrated, but the strips are (presumably to avoid manufacturing new meters) I know both my two are calibrated, and it refers to this in the technical details/specifications.
 
I have to admit I can't find a good reference to back up my memory of the 2010 figure. If anyone knows of a modern meter that reads whole blood I will stand corrected. Labs of course separate the blood so that they can measure just the plasma.
Did you mean coded rather than calibrated? I don't know if there are still any meters that require codes to be entered rather than have the correction factor for batches built into the strips.
 

I have never really known what "coded" means, hence never understood why the Codefree meter was so named. All meters read whole blood, then somehow convert the whole blood measurement to match plasma. So the reading we see on the screen is a plasma reading/estimate
 
As I understand it batches of strips were tested by the manufacturer and a correction code was provided with the strips which then had to be entered on the meter to get accurate readings for that batch. The strips are now programmed with the code so that it is effectively entered automatically. I guess the SD Codefree was named when this feature was a novelty.
 
lucas12 said:
Hi readings on the photo are from same blood drop as you can see even same type of meters can show the differenceView attachment 26054
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An adviser at Home Health (Code free) told me NOT to use the same drop of blood when re-testing, as it can have been affected by being exposed to the air. However I often do comparisons between my Codefree and TEE2 meters, as well as doing two tests with one of the meters, sometimes using the same drop of blood and sometimes a new one, and I have not observed any greater discrepancy by one method or the other. However, since she told me this I have tried to make haste when I re-use a single drop of blood. I do find it worthwhile to retest when I get an unexpectedly high reading. Sometimes the Codefree and TEE2 meters match each other exactly, in which case I am obliged to accept the reading as true, whereas without the second test I would have felt doubtful.
 
Alexandra100 said:
I suspect the main problem is with the strips, and it is no-one's job to make sure they match up to the standard required.
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Yes, agreed, and some of this is down to human error in addition to wonky strips. Some brands of strips are not at all user friendly and require manhandling to get them out of the tub, or out of the foil. By which time they can be corrupted. In a conversation I had once with Mr. Home Health (Codefree) he told me how horrified he is at some customers when he discovers they decant the strips into a different container. The tubs are specially designed to be as safe as possible as regards humidity etc. (which is why it is essential to snap the lid closed immediately after use). For this reason I love my Accu Chek Mobile and its fully enclosed cartridges that require no handling at all.
 
There are constant quality checks and checks of accuracy through independent research and medical standards organisations. Not all of it public but you can see which companies have been fined etc for failing to meet standards. The standards and technology is improving all the time with the freestyle libre being the start of major changes.

I do think meters help improve lives every day. Hypo's, DKA and being safe to drive to name a few.

I've been really happy with the 3 meters I have owned over the last 6 years.
 
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