Big difference between two testing meters. Which to believe?

[merrymunky]

Hello lovely people,

So today whilst I was at the maternity unit having my fortnightly consultation they upgraded me to a new glucose meter. I have been using the one touch select plus since diagnosis but they are ‘old’ and being phased out.

They’ve replaced it with an AgaMatrix kit with Bluetooth capability so I can use the app.

Out of interest I thought I would test tonight using both meters on the same blood sample. The results are alarming.

On my old device 5.9
On the new device 7.1

Now I am totally confused and don’t know which one to believe.

 

[Ljc]

I know it seems a lot but imo it isn’t. To me a variance of 1.2 means they are both in the same ballpark .
Unfortunately no meter we use is dead accurate.
However if you are worried , they may be a bottle of control solution included in the case, if not the manufacturer will send you some.

 

[merrymunky]

I know it seems a lot but imo it isn’t. To me a variance of 1.2 means they are both in the same ballpark .
Unfortunately no meter we use is dead accurate.
However if you are worried , they may be a bottle of control solution included in the case, if not the manufacturer will send you some.

Ther was a a bottle of control solution in the kit. I used it prior to this test as it states to do that before first use.
I just think it’s going to skew a lot of my radon’s if it’s that variable. It’ll be interesting to see the difference again tomorrow.

 

[Ljc]

They are variable due to being designed for home use rather than laboratory conditions, they do have to comply to certain uk standards. I forget what those regs are, I am sure someone else will know.

 

[Bruce Stephens]

I just think it’s going to skew a lot of my radon’s if it’s that variable. It’ll be interesting to see the difference again tomorrow.

I wouldn't have thought the difference was that big. Whether I get 5.9 or 7.1 doesn't change what I do: they're both fine, and if I'm going to do any exercise (like walk anywhere significant) I'll either eat something or be prepared to eat something on the way. (I guess that's mostly because I use a Libre so I'm looking as much at the direction as the specific value, but even when I just have test strips the difference between those two values isn't important.)

 

[Bruce Stephens]

I forget what those regs are, I am sure someone else will know.

Used to be (before 2016) +/- .83 for actual values lower than 5.6mmol/L and +/- 15% otherwise, at least 95% of the time. It's defined differently now (more strictly than that, obviously) but I can't find a good link.

 

[trophywench]

Have to say I had a tried and trusted One Touch meter which I was loth to give up but when I obtained a Roche pump, I really had to change and start using the handset/remote control/meter that came with it which I disliked because it always read higher. Amazingly 6 months later for the first time in my life I achieved my first HbA1c test under 7.5%!

OTOH MM with your old meter, you've achieved brilliant results so you could try asking One Touch for some control solution too, to test both meters.

 

[merrymunky]

Just done my waking test with both meters. One touch said 4.1, AgaMatrix said 4.7 so a bit closer this time.

 

[Andy HB]

Just use one meter. Or, if you happen to use two, just average the readings (oddly, this may even give a more accurate result!).

In scientific experiments there is always a level of error on every measurement. To get around this, one usually repeats the measurement multiple times and then takes an average.

Even using the same meter you will get different readings, by the way.

But, so long as the meter you are using is working as intended and the strips are ok, then just stick with the one reading. Well, unless you get a reading which is way off.

 

[merrymunky]

Just use one meter. Or, if you happen to use two, just average the readings (oddly, this may even give a more accurate result!).

In scientific experiments there is always a level of error on every measurement. To get around this, one usually repeats the measurement multiple times and then takes an average.

Even using the same meter you will get different readings, by the way.

But, so long as the meter you are using is working as intended and the strips are ok, then just stick with the one reading. Well, unless you get a reading which is way off.

Oh don’t worry I will eventually be switching full time to the AgaMatrix and putting the old meter to bed. My pregnancy consultants will only be looking at the AgaMatrix data from now on anyway. I was just interested to see the difference in results and was startled by the massive difference yesterday as it made me wonder if my old meter had been giving too generous readings which could be causing me to eat more than I need to as I often have lost meal readings still on the 5s so would snack on something else to raise it a little before bedtime. Don’t want to be sending myself higher than I should be and not realising it.

 

[SweetGuy]

My understanding was that meters can begin to underestimate as they get older and you should get a new one every two years.

 

[Andy HB]

My understanding was that meters can begin to underestimate as they get older and you should get a new one every two years.

I strongly doubt that. The test strips are the things which do the work and it is those which become unreliable when they age (that's why they have a use by date). The meter itself is just a piece of electronics.

 

[SweetGuy]

I strongly doubt that. The test strips are the things which do the work and it is those which become unreliable when they age (that's why they have a use by date). The meter itself is just a piece of electronics.

This came from a diabetic nurse specialist who was mildly shocked to learn I had been using the same meter for about the last 8 years. When I compared a new meter to the old from the same blood sample the old meter was consistently significantly lower.

 

[Andy HB]

Interesting. Maybe the slot that the test strip goes into wears out over time? It'd be good to know because this is the first time that I've ever heard this.

Just Googled lifespan of glucose monitors. The thing I read said three to five years. But one very good suggestion was to periodically check the meter and test strip with the control solution. 🙂

 

[Northerner]

This came from a diabetic nurse specialist who was mildly shocked to learn I had been using the same meter for about the last 8 years. When I compared a new meter to the old from the same blood sample the old meter was consistently significantly lower.

Companies upgrade their meters from time to time, usually with better accuracy or to comply with stricter regulations, so that may lie behind the advice to change every couple of years or so 🙂

My Contour Next is consistently 1-1.5 mmol/l higher than my Freestyle Libre reader (on a blood test). In the scheme of things it's not a huge difference so I tend to 'trust' whichever one I'm using as my 'main' meter. Before the Contour I had an AccuChek, and that was different too! 🙄

 

[grovesy]

This came from a diabetic nurse specialist who was mildly shocked to learn I had been using the same meter for about the last 8 years. When I compared a new meter to the old from the same blood sample the old meter was consistently significantly lower.

Well they did did change the standards on them a few years back so yours might not have been up to current standards.

 

[everydayupsanddowns]

I'm not sure if it's the same model @merrymunky, but the Agamatrix seems to perform pretty well in this US comparison from a few years back

https://diatribe.org/are-blood-glucose-meters-accurate-new-data-18-meters

 

[Robin]

I’ve had my meter at least 8 years 😱 but it’s still going strong, and it quite often tallies exactly with my Libre.

 

[merrymunky]

I’m just going with it for now.
I’m definitely coming out higher than I would on my one touch but that’s ok as long as it’s consistent.

I am waiting for the doctor to add the new items to my mediation list so I can order new test strips. I’ll be out of them by weekend and I need to give a week notice when ordering so that’s fun. Might have to use my old one next week at this rate.