Variations in bg readings/faulty meter?

[suevm]

I've recently had a strange experience with my bg meter/monitor. Last weekend I had a reading of 17 - which is rather high for me. I immediately repeated the test and the reading was 10. The puzzled me, so I repeated it again and got 12 and 8. I can see that readings could vary slightly, but these were huge variations.
I have now been given a new meter/monitor by my GP, which is the same type (presuming the first one to be faulty). I thought the problem was solved, but I found the same thing again with the new one, although the variations have not been so extreme yet. However because of this I have lost confidence and always do 3 tests in a row and take the average!
Is this a common problem? Has anyone else experienced this?
Btw, I am quite new to diabetes and bg testing.

 

[everydayupsanddowns]

Hi Sue

There are many reasons why home BG monitors can sometimes give rather patchy results.

First of all... your blood is not an entirely evenly mixed solution, so testing a few moments apart and from different fingers can be sampling 'different' blood.

Secondly the strips themselves have manufacturing variation. The enzyme-y gloop that they spray on the little absorbent slurpy bits cannot be guaranteed to be at absolutely identical concentrations all the time. To conform to ISO standards the meters and strips themselves must give readings within + or - 20% variation from a lab test 95% of the time. So 5% of the time they can give you any number at all (that's about 2 strips per pot). Obviously with a % variation... the higher your reading, the greater the apparent variability will be - at 12.0 tests from the same drop of blood recording either 14.4 or 9.6 would be equally valid under the 2003 ISO standards (newer meters under ISO 15197:2013 are required to meet +/-15%).

Thirdly and perhaps most importantly of all... there is user-error. I don't know about you, but I dont *always* wash and dry my hands before testing. And temperature... humidity... strip storage and calibration (if required) can all affect the accuracy of a test.

Essentially they are a vague guide only, and for the most part they are plenty accurate to manage D. It is annoying that all the precision of modern treatment options are not being fed accurate date, but they are all we have at the moment. If a test doesn't agree with how you are feeling, then retest to check it. But don't expect both tests to give 100% the same number. I certainly wouldn't advise 3x tests each time. You will burn through the test allowance of even the most supportive GP in no tme and IMO you would be better off spreading your resources to cover more parts of your day (pre and post meals for example).

Hope that helps 🙂

 

[suevm]

Yes, thank you, that's very informative. You've explained it so well. Apparently, according to my GP, this particular monitor has given other patients problems too. So anyway, I now have a new monitor (different type) and will stick to one test at a time....unless it looks/I feel strange.
This new one also tests for ketones, but I don't think that will be necessary much or not at all. I still seem to be a 'complicated' diabetic......type 1, type 1.5.......they can't decide what I am!
Anyway, thanks again for your reply - much appreciated.

 

[trophywench]

Oh well Sue, give em chance, certain blood tests take absolutely months and months to get the results - eg I know C-peptide does, it just isn't done in most labs only specialist ones - so perhaps there are things they need to test for 1.5 that are similar?

 

[AlisonM]

I got the results of my C-peptide and GAD tests in three weeks and that was even though they had to send the doings to Glasgow. I think it all depends on what level of service is available in your area. Things have improved here in the last year and blood tests are normally back within three or four days. Which is good because they're always wanting blood from me for one test or another. I average about one a month it seems.