Accu Check Mobile - Odd results

[ElyDave]

the reason I got the accu-check mobile was because it was all nicely integrated and an easier package to use when carrying out sports, so I've been trying to get it calibrated vs the glucomen LX. When I used it to cycle home the 25 miles from Addenbrokes on Friday, no problems, but both of the last two times I've used it at home before workouts in my gym it;s given me odd readings.

So last night, pre rowing - Accu-check (AC) 4.0 , Glucomen (GM) 5.6
post rowing - AC 5.4

Today - pre turbo trainer - AC 4.0, GM 5.2
post - AC 7.4, GM 8.4 - It was an interval session with a big liver shunt

Anyone had similar experience of doubtful accuracy with an accucheck? The only thing I can think is lower blood flow to my fingers pre-exercise, or cooler extremities.

 

[mo1905]

Dave, how do you know it's doubtful accuracy of the Accu-check ? Could it be the other way around ? The Glucomen reading wrong ?

 

[Garr]

I use both meters too, mobile mainly for in the car, I tended to get wider variance at high readings (above 6 ish) but very similar at lower. Not compared for a while though.

 

[Garr]

Just tested now, GM 6.9, Mobile 7.3, not bad.

 

[ElyDave]

Thanks Garr

Mo, if the glucomen was reading high then that means that I've been running in significant hypo territory for much of the last 6 months with no symptoms. The fact that the glucomen is self-consistent and also consistent with the accuchek post exercise suggests that there's something about odd about the circumstances of my pre-exercise checks.

 

[noblehead]

When the Accu-Chek Mobile first came out I used it for a short time, apart from it being big & bulky I found it was reading higher than the Aviva meter which I had been using, so it went in my bedside drawer and hasn't been back out since.

However the truth of the matter is your never going to get two meters giving identical readings, you can test yourself twice in a row using the same meter and still get different readings, that is why they say stick with one meter and do a control test if you doubt the accuracy.

 

[angieG]

There will always be discrepancies between meters as none are totally accurate.
I have 2 Accu Check Mobile meters and use them both all the time and they can't agree between them with often a variation of 0.5 when up around 8 or so.
There seems to be variation depending on the uptake of blood onto the cassette too. The other day I tested before lunch and got about 3.3 despite feeling fine, strange I thought I don't feel like that so immediately re-tested from same finger with the same machine and got 6.2 (that is more how I felt).
The annoying thing is I am a coach driver and 3 months of my readings have to be checked by a Consultant for my DVLA report so that 3.3 would be logged as a hypo as there is no way on the machine to record it as a false reading. Quite worrying that DVLA could put you out of work due to general meter inconsistencies!!

Angie

 

[noblehead]

There seems to be variation depending on the uptake of blood onto the cassette too. The other day I tested before lunch and got about 3.3 despite feeling fine, strange I thought I don't feel like that so immediately re-tested from same finger with the same machine and got 6.2 (that is more how I felt).

Angie, does the Mobile not come up with an error message when not enough blood has been applied, normally the Accu-Chek meters do :?

If it doesn't then this is something to bring up with Roche for the reasons you mention above.

 

[angieG]

Hi noblehead,

Yes the meter does come up with an error if there is not enough blood applied so that is not the problem.
It seems to vary depending on how much is absorbed onto the cassette tape sometimes, or maybe it's the quality of the blood from the finger (which does vary depending on temperature / squeezing etc) but I know there are times when I have had an unexpected result and re-tested immediately to find it about 2.0 different. I have even tested twice on one meter and twice with the other and all 4 readings were different within a range of about 3 or 4.

It is okay if DVLA take this sort of thing into account but if they take every reading as totally accurate it could cause problems. If I get what I deem to be an incorrect low reading I always test immediately again so if it turns out quite a bit higher it shows there could be some error as even pure sugar wouldn't work that quick.

Regards
Angie

 

[noblehead]

Hi noblehead,

Yes the meter does come up with an error if there is not enough blood applied so that is not the problem.
It seems to vary depending on how much is absorbed onto the cassette tape sometimes, or maybe it's the quality of the blood from the finger (which does vary depending on temperature / squeezing etc) but I know there are times when I have had an unexpected result and re-tested immediately to find it about 2.0 different. I have even tested twice on one meter and twice with the other and all 4 readings were different within a range of about 3 or 4.

It is okay if DVLA take this sort of thing into account but if they take every reading as totally accurate it could cause problems. If I get what I deem to be an incorrect low reading I always test immediately again so if it turns out quite a bit higher it shows there could be some error as even pure sugar wouldn't work that quick.

Regards
Angie

I think I only used one cassette (possibly 2) that came with the meter before deciding I wasn't happy with it. What you say about squeezing the finger makes sense as I've read this before that it can effect bg readings, wasn't aware about temperature though as usually the meters won't operate if temp rises or falls below a certain level.

That's a good idea to take another reading immediately after if you suspect the first reading was inaccurate, if anything it will help the DVLA in their decision making.

Thanks for the reply btw

 

[drahawkins_1973]

I have an 2 meters too and my original true result test kit I got when first diagnosed always gives readings about 1 mmol below my new Aviva test kit.
I understand why the DVLA want to make sure that we are safe to drive but it is a bit of a farce that you can test and retest until you give the 'ok' reading and then go. In reality you could drop under 5 within 2 hours but you'd still be following the rules.
But I don't know what a sensible alternative would be. I'm still new to this and I'm sure there are lots of posts about this previously. But agree that you are doing the right thing by checking and err on the side of caution and be sure you're ok.
How to educate the DVLA is a totally different challenge.
Sorry that isn't a particular helpful reply but I just wanted to say I really get your frustration.


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[drahawkins_1973]

I have an 2 meters too and my original true result test kit I got when first diagnosed always gives readings about 1 mmol below my new Aviva test kit.
I understand why the DVLA want to make sure that we are safe to drive but it is a bit of a farce that you can test and retest until you give the 'ok' reading and then go. In reality you could drop under 5 within 2 hours but you'd still be following the rules.
But I don't know what a sensible alternative would be. I'm still new to this and I'm sure there are lots of posts about this previously. But agree that you are doing the right thing by checking and err on the side of caution and be sure you're ok.
How to educate the DVLA is a totally different challenge.
Sorry that isn't a particular helpful reply but I just wanted to say I really get your frustration.


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[angieG]

noblehead,

I was refering to the temperature of my fingers not my meter
I don't think I have much blood in my fingers at some temperatures :shock:

It is a handy meter for being on the road as you can do quick tests without having to fiddle about with strips and separate lancets.
My Diabetic Clinic did offer me the Accu check that calculates bolus's after I did the carb counting course which would still be okay as it stores 3 months and they can download the data but it uses strips again so I turned it down.

Regards
Angie

 

[drahawkins_1973]

Maybe you can stick one hand under your bottom (or somewhere else warm ) before taking a reading and the take one from each hand to calibrate.


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[ElyDave]

Hi noblehead,

Yes the meter does come up with an error if there is not enough blood applied so that is not the problem.
It seems to vary depending on how much is absorbed onto the cassette tape sometimes, or maybe it's the quality of the blood from the finger (which does vary depending on temperature / squeezing etc) but I know there are times when I have had an unexpected result and re-tested immediately to find it about 2.0 different. I have even tested twice on one meter and twice with the other and all 4 readings were different within a range of about 3 or 4.

It is okay if DVLA take this sort of thing into account but if they take every reading as totally accurate it could cause problems. If I get what I deem to be an incorrect low reading I always test immediately again so if it turns out quite a bit higher it shows there could be some error as even pure sugar wouldn't work that quick.

Regards
Angie

Oi - stop hijacking my thread .

Only kidding, just goes to show I'm not the only one, and I wonder the same issue, once I've warmed up with plenty of blood flowing it's not an issue, but it does seem as if my pre-exercise "cold blood" is not as good.

 

[ElyDave]

Maybe you can stick one hand under your bottom (or somewhere else warm ) before taking a reading and the take one from each hand to calibrate.


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Where's that "like" button again?

A bit difficult though on a bike.

 

[drahawkins_1973]

Do you mean a bike as in motorbike or a bike as in a cycle?? Sorry if that sounds really rude but I was just try to envisage the best way to warm your hand


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[ElyDave]

bike as in cycle, easy enough to stop and warm my hand if alone, not so much if cycling in a pack.

 

[Book_woorm]

Some of the differences in the readings of these machines can be explained by the tolerances to which they work. I was reading an article the other day about 'continuous' BG monitoring that was saying that the reason that there are not many such devices was because it was difficult to get them to work the required tolerances! It turns out that below a BG of 5.6 the meters are supposed to be better than +/- 0.85 and above 5.6 better than +/- 15%. In engineering and scientific terms these tolerances are ridiculously wide.

So for example if you are using two meters one could read 4.75 and the other read 6.45 and they would both be right as far as the manufacturers are concerned because they are within tolerance!!!! Next time you do a control test don't just tap in the colour code of the control solution but actually look at the numbers on the box and on the machine, its quite eye opening.

I see three problems with this

A) If like me you don't feel the effects of a Hypo until your BG has dropped to something like 3.5, a reading of 4 could actually be 3.15 which is well into hypo territory. Even worse it could say 2.4 and you could be as low as 1.58 which is brain damage territory!
Of course the reverse could also be true if I'm feeling fine at a meter reading of 3.5 it could actually be 4.35! buts lets err on the safe side and out with the mars bars at that point.

B) If you just use one meter then you would think that it would read consistently high (or low) and thus you would marginally under or overdose until you adjusted your ratios and be none the worse for it. BUT and its a big BUT these machines are not consistent. As stated above two readings in quick succession can give wildly different answers. You just have to find out how wide the spread of the results is that you are getting. Then you can come up with a second partial 'Correction Dose' figure that relates to the level of error on your meter which in turn can tell you how different from what you expect the next test might be.

C) Using two meters is an even bigger recipe for gross fluctuations in your readings because you will never ever get a consistent pattern to learn what your ratios should be.

 

[ElyDave]

let's get back to where I started

Accu chek - pre exercise 4.0, Glucomen 5.6

Post exercise difference of <0.5 mmol/l

second session - accucheck 4.0, Glucomen5.2
Post exercise difference of 1.0

I guess that could be within tolerances, but it just seems odd that the acucheck reads low pre exercise. I have some calibration solution for each of them so will run them through that tonight.

As for meter accuracy, yes, you're right. When I'm used to working with metering uncertainties of less than 1.5% in some cases, these BG meters are horrible by comparison