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Conflicting meter readings - now really confused

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DannyB

Well-Known Member
Messages
45
In an attempt to get a better control over by BG I am now testing post-prandial on a regular basis.

I have two different meters:
- Accu-Chek Compact Plus
- Freestyle Lite

I am getting quite different readings from the two meters on blood from the same sample. For example:

Accu-Chek: 5.4
FreeStyle: 7.1

Accucheck: 5.6
Free Style: 6.7

Needless to say I prefer the Accu-Chek results - but how do I know which is right? I am trying to avoid a visit to the GP until I have 3 good months of results.

Now I realise that they both have quite a wide margin of error but I would still expect the two results to be at least close to one another. I have tested both meters with Control Solution and both are OK.

Anyone experienced anything similar? Any bright ideas other than getting a third meter to try to see which that agrees with (sod's law says I will proably get yet another different figure :? )
 
One difference is that the accuchek reports the level as the amount of glucose in whole blood, the freestyle (by an internal calculation) reports the amount of glucose in plasma.(as do laboratories)
The Freestyle should therefore read about 11-12% higher than the accucheck but this doesn't account for the whole difference.

On top of this meters only have to be accurate up to 10% either way!

I use an accuchek and have found it to be on average quite accurate ( HbA1c seems to reflect its results) but even then, every now and then it gives me a result that seems totally improbable and I end up having to retest.
 
Wow - now I am even more confused :D

Thanks for the reply. Can you explain a little more about how the whole blood/plasma readings work.

I had heard about the two different methods of measuring but assumed that the meter using the whole blood method did some kind of internal calculation to 'adjust' the result to give a 'pseudo' plasma reading. Have I misunderstood that?

Does that mean I am not comparing like for like with the two meters?

Which figure is the one I should be concerned with:
- whole blood
- plasma

Every time I think I am getting to grips with this something else pops up to send me a few steps back :D
 
Danny,

As I understand it, all meters use a whole blood reading, it's just that some perform a "behind the scenes" calculation to convert it to a plasma blood reading.

It shouldn't matter which reading you take note of as long as you know which one you're looking at. For instance, when people recommend a PP BG reading of 7 or less, are they referring to a plasma reading or whole blood? If it's a plasma reading and you have a whole blood meter then it's simply a matter of dividing the figure by 1.12 so that a plasma BG reading of 7, for example, is a whole blood reading of 6.3 (6.25 rounded up).

More information about your meter and whether it reports whole blood or performs some computation behind the scenes to calculate plasma levels can be found either in your meter manual, or in the information leaflet that comes with your strips (Abbot, for example, include this information with the test strips).

Regards, Tubs.
 
When members on this forum discuss BG levels are they normally referring to whole blood or plasma figures?

I assume one of these figures is the more commonly used.
 
:D Although it is dangerous to assume anything, I assume a plasma reading, but if you're not sure, ask.

Regards, Tubs.
 
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