Same Hand, Different Fingers

[TerryP]

Hi, I'm puzzled. I'm T2 and I have just finger pricked 2 different fingers on the same hand within 20 seconds of each other. (enviornmental conditions were the same) but got different readings. Finger #1 came in a 15.6 and Finger #2 came in a 14.1
How is this possible and which reading should I use. (I know they are both high but that's a different discussion)

Thanks

Terry

 

[Leadinglights]

That is within the accuracy of the monitor and are essentially the same.
There is a table somewhere showing the range that any given reading would represent. I will see if I can find it.

@Docb could you point us in the right direction for your table of monitor variation.

 

[TerryP]

O

That is within the accuracy of the monitor and are essentially the same.
There is a table somewhere showing the range that any given reading would represent. I will see if I can find it.

Ok thank you.

 

[Eternal422]

Hi Terry, I’m afraid it will be variable. Even taking a finger prick from the same finger will give different readings. The meter is just reading the blood glucose within the drop of blood you get, blood glucose will not be at a constant level throughout the body and certainly not in the capillaries where you get it from with a finger prick test.

As @Leadinglights has said, the meter’s accuracy comes into play as well, I seem to remember seeing figures of a Mean Absolute Deviation of meter readings as being ±15% which means that if a lab test gives you 6.0 then it would be acceptable for a meter to read anywhere between 5.1 and 7.

To be honest the difference between 15.6 and 14.1 is really neglegible.

 

[Sally71]

The meters are not as accurate as you think they are, the decimal point is a bit deceiving. By law they only have to be accurate to within 15%, the chance of you getting two identical readings even from the same drop of blood is tiny. If you had one that read 6 and one that read 15 then I’d worry about it, but as close as yours are is basically the same.
@Eternal422 can type faster than me!

 

[everydayupsanddowns]

Hopefully this from the ‘Useful links’ thread might help explain things @TerryP 🙂

BG meter accuracy
It can be quite disconcerting for members new to self monitoring of blood glucose to get different results from BG readings taken close together, even when carefully following manufacturers guidance (washing hands etc). All meters for sale in the UK should comply with the following ISO standards 95% of the time, which allows a degree of variation (and 5% of results can read anything at all). If in any doubt, or if a reading doesn’t match how you are feeling, you should check again with a fresh strip.

 

[Docb]

@TerryP - some time ago I did all fingers (and thumbs) one after the other and found the same sort of variability which you have found. Since then I have rounded single results to the nearest whole number when quoting single readings - anything after the decimal point is meaningless. Can't remember the exact numbers but you would need a difference between two single readings to be around 3-4 units for them to be significantly different statistically.

Some might think that this makes the monitors poor. I don't. I think it is absolutely amazing that they can get anywhere near measuring a blood glucose level and get a reproducibility that good.

Your interpretation that they are both higher than you would want is by far the most important thing to take from those numbers!

 

[Deleted member 21371]

Hopefully this from the ‘Useful links’ thread might help explain things @TerryP 🙂

BG meter accuracy
It can be quite disconcerting for members new to self monitoring of blood glucose to get different results from BG readings taken close together, even when carefully following manufacturers guidance (washing hands etc). All meters for sale in the UK should comply with the following ISO standards 95% of the time, which allows a degree of variation (and 5% of results can read anything at all). If in any doubt, or if a reading doesn’t match how you are feeling, you should check again with a fresh strip.

I'm not actually sure they need to comply with the most recent standards, so long as they specify with version they do comply with.
It a very hit and miss thing.