Differences in meter readings.

[peekawho]

Just curious about this, b/c it has become an issue for one of our long term gestational diabetics in the hospital.

She likes her own meter, and her lancets are far less painful than our hospital ones.  Her doc said she could use her own equipment as long as it corrolated well with our hospital meter.  The problem is, it doesn't.  A couple of readings will be within a few points, and then there will be one that is 20 to 30 points off!  
She can't use her lancets for our meter, since the hospital meter takes much more blood to register than hers.

I'm just interested in why the big difference in the readings.  She is using the same finger poke to do a reading on her meter and ours.  I've watched her technique, and she is doing everything correctly.  We ran controls on her meter (which is only 3 weeks old) and it seems fine, as is ours.  

We have to go by our meter readings when she is hospitalized for her insulin sliding scale.  But she says at home, she has to go by her meter, and is now concerned about which is "right".  

[Forum-VOL-LS]

Hello Peekawho -
We're volunteers here and not medical professionals.

Each meter/strip combination that I've used has a statement about the 'range' within with it assures accuracy.  Often that statement is included on the package insert for the strips and in the insert for the meter itself.  As I recall, the range can be as high as 20%.

Our home-use strips are terrific for us to know how we're doing in general, where a reading of 100 might not suggest a different course of action than a reading of 120.  Similarly, a reading of 300 suggests a similar course of action as a reading of 360 -- tho' clearly the amount of insulin to treat that would vary a bit.  I've used home testing for over 25 years and have come to rely upon (1) the patterns of test results, and (2) physical cues I get from my own body.  

A difference of 20-30 points between the hospital meter & the patient's meter can be well within the 20% range -- since each meter will have a range.

Here's an example using some estimated numbers.  If her meter shows 100, the actual reading might be between 85-120.  If the hospital meter shows 130, the actual reading might be between 110 - 156.  So, with an actual bloodsugar of somewhere between 110-120 both meters would be 'right' and with an actual of 110 -120, getting a reading of 100-130 is pretty good.  

Hope this helps...

[peekawho]

So far we've tried having her do her reading on the first drop of blood and ours on the second, and vice versa.  We've tried doing them simultaneously on different fingers.  

Sometimes the readings are very close, sometimes way, way off.  There doesn't seem to be a pattern.  

And no consistency in the differences.  So we are forced to just use ours, which she hates b/c of the larger and more painful lancet.  

I tried bringing my husbands meter in, and comparing results from me vs the hospital meter.  Once, almost exactly identical readings, and 2 minutes later...15 points off!   Our meter is QC'd every 8 hours at the hospital.   According to the lab and biomed, its fine.

[peekawho]

Sorry, I typed that last as you were giving your excellent answer.

Unfortunately then, I guess we'll have to use ours.  She's on a strict sliding scale, and a blood sugar of 120 calls for a significantly different insulin dose than 100.  

I see where you're coming from, though.  For a well established and controlled diabetic, it isn't as crucial.