Different reading every time I test?

[pab99c]

Hi,

Diagnosed T1 less than a week ago. Since then I've absorbing as much information as possible. Lots to learn!!

Question, is it normal to get a different reading every time I test?

i.e. I tested myself, and I was 2.9 - eek I thought, so I tested again immediately, then I was 4.7, tested again 5.9, tested again 4.1.. all within a 5 minute period.

Using a Contour USB. I tested it using the "normal" solution and it seems to be working fine.

Any thoughts?

Thanks,

Paul.

 

[Hobs]

Do you make sure that the finger to be tested has been washed rinsed and dried before lancing?

 

[pab99c]

nope I didn't on that occasion..

 

[Hobs]

So you've answered your own question.

 

[Otenba]

No, hand washing can make a difference to getting reliable blood testing results.

On top of that, there is a teeny tiny error margin on all blood testing machines so for you to get roughly around the same range is reasonable. This error margin is stated in the instructions of every blood testing machine. A machine that is 100% accurate does not exist (yet).

 

[Grazer]

You can also get unreliable varying results if you squeeze near the puncture site to get blood.

 

[pab99c]

Thanks for the advice guys.

 

[Sid Bonkers]

On top of that, there is a teeny tiny error margin on all blood testing machines

According to ISO 15197 Blood glucose meters must provide results that are within 20% of a laboratory standard 95% of the time.

I would hardly call 20% a "teeny tiny error" A Real bg level of say 6 mmol/L could be recorded as 7.2 mmom/L or as 4.8 mmol/L. And that is 95% of the time which really means that for 5% of the time the accuracy can be even less or one particular meter could be out by much more than 20%.

They are designed to give the home user an idea of their current bg level they are NOT 100% accurate.

Which is why it is almost impossible to get the same reading from two different meters even when using the same drop of blood and why it is quite common to get 3 or 4 different readings within a 5 minute period.

 

[AMBrennan]

A Real bg level of say 6 mmol/L could be recorded as 7.2 mmom/L or as 4.8 mmol/L.

Technically true, but ultimately irrelevant since it would not affect treatment*. You also conveniently forgot to mention that meters need to be more accurate for lower level (<4 mmol/l) i.e. when it affects immediate treatment decisions.

* You can only adjust insulin dose in 1u increments. Knowing that you should, ideally, have taken an additional 0.24u of insulin with a given meal will be absolutely useless in practise (unless you are using insulin pumps that allow for more precise bolus)

On the other hand, my Freestyle consistently reporting BG levels that are 1 mmol/l lower than my Optium does worry me.

 

[Otenba]

Oh, sorry for not being exactly accurate Sid.. I was posting information off the top of my head and I just knew it varied from machine to machine so wasn't happy to post percentages!

The last discussion I had about it established that the difference was tiny when it came to the big picture (eg, 20% of 5BG is tiny if you think about it - the higher you are, the more out your results are!).

Simples!