Different meters different readings

[DianaMC]

I thought I would see if Ascensia would be happy to send a free glucose meter to me as a prediabetic and they were! So I was quite pleased to see my slim, shiny Contour Next One arrive in the post. But I’m noticing differing readings from the Accu Chek I was using - which was not new; given by a friend when I first wanted to get going with testing blood sugar levels. But to our knowledge nothing wrong with it - her family gets through a lot of meters as two people are diabetic (type 1 and 2/gestational).

Has anyone else had variations like this? As examples, today’s readings (mol/l):

Before breakfast
Aviva 5.3
Contour 5.8

1 hr 20 after breakfast
Aviva 6.2
Contour 7.5

2 hours after lunch
Aviva 6.4
Contour 7.3

The Contour Next readings consistently come up higher, as you can see.

The only thing different that I can put my finger on is that the test strips for the Contour are harder to get into the meter, without touching the tip at all. I’m not sure if accidentally touching the section where the blood goes would make a difference. And maybe that doesn’t happen every time. The readings are still higher than on the other meter.

 

[MeiChanski]

Hello,

I tend to find different meters vary in readings and accuracy, with a difference of 0.5-1.0mmol/l, which doesn't mean much and it seems okay in my opinion (nothing to worry about). It'll be questionable if it was a difference of 2-3mmol/l.

 

[Deleted Account]

Meters need to be accurate to within +/-15%.
Some meters will give slightly higher readings and some slightly lower readings and you may be comparing one of each.
As the allowed variance is a percentage the actual different becomes greater as the BG value because greater.
For example, if your BG is actually 7.0, the meter could read anything between 6 and 8.

With this in mind
1. Your meters do not look far out
2. You should use one meter rather than swapping between them
3. Whichever meter you use, the important thing to consider is the trends rather than the absolute value

 

[Bittern]

Meters have a +/- 15% tolerance so comparing different meters will, in all probability, give different readings. The worst case would be a difference of 30%. So with one reading 5 the other could read 6.5 both are just in tolerance albeit at the extreme ends. Pick one and stick to it use it for testing before and after meals and for spotting trends.

 

[Rustytypin]

I have accumulated a total of four meters over the past three years, one of which is a Contour Next, which I used as my main meter. However I have stopped using it as it consistently read about 0.5 mmol higher than the other 3. This was especially true of the fasting BGs, where it would be up to 1 mmol higher! To test I would use the same drop of blood, so hopefully the reading would be comparable.
I now am using a Tee2, as its strips are about half the price of the Contour.

 

[Bluetit1802]

My advice is to put one of the meters away to be used as an emergency spare. Stick to one. No meters are 100% accurate and only need to meet the plus or minus 15% variant. You are unlikely to find 2 meters that have identical readings. You are also unlikely to find that one meter produces the same reading on immediate consecutive tests. All we are doing is trend spotting. Unless you need results to inject insulin, it really makes no difference in the end. Over a period of time, swings and roundabouts, the averages will work themselves out.

 

[Scott-C]

Hi, @DianaMC and @Rustytypin , thought I'd pitch in with a few comments on bg testing and meter accuracy.

There's two ways of looking at this.

The first way is to look at technical studies comparing various meters and see how they measure up according to industry standard tests.

For example, there's a fairly recent one, linked to in this article:

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

Contour Next comes out on top as being the most accurate.

You've both mentioned that meter, and, if that was how you choose to judge it, that should be be your preferred meter.

But the other way of looking at it is this: the technical differences between all the main contenders are just that: technical differences.

In the real world, the plain truth is that no meter is really all that accurate.

All of them, no matter how fancy their marketing is, or where they are placed in technical tests, just provide broad indications of general ranges.

They are accurate enough for that purpose. I'm T1, so am looking at it from a slightly different perspective.

I'm broadly interested in knowing whether I'm sub-4, between 4 to 7, or above 9.

If I see 5.3 on the meter, and test again at 5.8, or even 6.2 or whatever, those will all be the same number to me: I'll read it as "about 5 to 6", which is good enough for my purposes, as, even though I don't know for sure where it lies after the decimal point, it doesn't matter, because I can be reasonably certain it isn't 3 and it isn't 8.

I use that approach in my T1 world. Meters don't get any more accurate when used by T2s, pre-diabetics, LADAs, or whatever: meters are meters whoever is using them.

Sorry, been waffling on a bit, the point I'm trying to make is that the decimal point accuracy which many newbies look for in bg measuring simply doesn't exist with the current technology, the best you're going to get is a broad range indication, which is actually good enough for most purposes.

I've seen posts from people who've driven themselves mad seeking an accuracy which just doesn't exist in this field.

Learn how to read them for what they are: broad indicators. Near enough is good enough. They are still very useful, despite their limitations.

 

[Rustytypin]

Hi, @DianaMC and @Rustytypin , thought I'd pitch in with a few comments on bg testing and meter accuracy.

There's two ways of looking at this.

The first way is to look at technical studies comparing various meters and see how they measure up according to industry standard tests.

For example, there's a fairly recent one, linked to in this article:

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

Contour Next comes out on top as being the most accurate.

You've both mentioned that meter, and, if that was how you choose to judge it, that should be be your preferred meter.

But the other way of looking at it is this: the technical differences between all the main contenders are just that: technical differences.

In the real world, the plain truth is that no meter is really all that accurate.

All of them, no matter how fancy their marketing is, or where they are placed in technical tests, just provide broad indications of general ranges.

They are accurate enough for that purpose. I'm T1, so am looking at it from a slightly different perspective.

I'm broadly interested in knowing whether I'm sub-4, between 4 to 7, or above 9.

If I see 5.3 on the meter, and test again at 5.8, or even 6.2 or whatever, those will all be the same number to me: I'll read it as "about 5 to 6", which is good enough for my purposes, as, even though I don't know for sure where it lies after the decimal point, it doesn't matter, because I can be reasonably certain it isn't 3 and it isn't 8.

I use that approach in my T1 world. Meters don't get any more accurate when used by T2s, pre-diabetics, LADAs, or whatever: meters are meters whoever is using them.

Sorry, been waffling on a bit, the point I'm trying to make is that the decimal point accuracy which many newbies look for in bg measuring simply doesn't exist with the current technology, the best you're going to get is a broad range indication, which is actually good enough for most purposes.

I've seen posts from people who've driven themselves mad seeking an accuracy which just doesn't exist in this field.

Learn how to read them for what they are: broad indicators. Near enough is good enough. They are still very useful, despite their limitations.

Hi Scott, Thanks for the full explanation, I am aware of the limitations of the BG meters, I decided to ditch the Contour after nearly three years, not because of absolute accuracy, it does give “expected” results, but largely because of the cost of the strips. Full price is about £20 per 50 strips (or £12 for unknown quality from EBay), the Tee2 less than half that. Also as I mentioned above, it is consistently higher than the other 3 meters.

 

[DianaMC]

Thank you to everyone who commented on this issue. I found all your comments helpful to hear.

I get the general idea - broad ranges rather than exact measures. That’s useful to know.

Also glad that I seem to have ended up with a meter considered to have a high level of accuracy. I didn’t know they really differed in that way. I was just wondering if one was malfunctioning. Hence the clarification is very useful. Thanks for posting that link, @Scott-C

The test strips for both my meters are costly. If I was needing to do testing all the time I’d probably consider a meter with cheaper strips, as I do have to buy all the supplies (no free scrips). But, at the moment, I’m just trying to get an idea every so often and/or with regard to specific foods. And the broad range approach probably works for what I need. So I guess these suit me for now.

Thanks again.

 

[zauberflote]

Thank you to everyone who commented on this issue. I found all your comments helpful to hear.

I get the general idea - broad ranges rather than exact measures. That’s useful to know.

Also glad that I seem to have ended up with a meter considered to have a high level of accuracy. I didn’t know they really differed in that way. I was just wondering if one was malfunctioning. Hence the clarification is very useful. Thanks for posting that link, @Scott-C

The test strips for both my meters are costly. If I was needing to do testing all the time I’d probably consider a meter with cheaper strips, as I do have to buy all the supplies (no free scrips). But, at the moment, I’m just trying to get an idea every so often and/or with regard to specific foods. And the broad range approach probably works for what I need. So I guess these suit me for now.

Thanks again.

One more, just agreeing with your experience. I have three. Two are store brand with inexoensive strips. The third was a test because I couldn't believe what the dr said my HbA1c was. I still don't, because then I bought a home HbA1c test kit and it was lower as well!
The two store brand ones: my daily driver is consistently 2-7 US points higher, of the two. The other one lives at a vacation spot.
The third one read much lower than either store brand, but was consistently within the lower 15% accuracy zone of the daily driver. I only used it for a few days as the strips were obscenely expensive. They are both American brands.

Just confirming your experience!

 

[DianaMC]

Thanks @zauberflote I’m fascinated that your home HBA1c test kit showed a lower level than the Dr’s one!

 

[Bluetit1802]

Thanks @zauberflote I’m fascinated that your home HBA1c test kit showed a lower level than the Dr’s one!

So have mine, but they agree with my finger pricking and also with the Libre after mentally adjusting the readings because the Libre always reads slightly low for me. My surgery HbA1cs are always considerably and significantly higher. I am not alone in this.

 

[Eline]

As long as the differences are not massive, I would not worry about it to much. However if you do find it unlikely high on multiple occasions it wont hurt to compare with another meter. Then taken into account the 15% range of accuracy, you can somewhat make a comparison.
I agree with Rustytypin on the Contour next: too high readings for me, I stopped using it.

 

[Bluetit1802]

As long as the differences are not massive, I would not worry about it to much. However if you do find it unlikely high on multiple occasions it wont hurt to compare with another meter. Then taken into account the 15% range of accuracy, you can somewhat make a comparison.
I agree with Rustytypin on the Contour next: too high readings for me, I stopped using it.

If there is a huge difference, or a very high (or low) reading that is unexpected, my suggestion is to re-test with the same meter. They all throw out rogue readings from time to time, and bringing spare meters into play muddies the waters.

 

[DianaMC]

So have mine, but they agree with my finger pricking and also with the Libre after mentally adjusting the readings because the Libre always reads slightly low for me. My surgery HbA1cs are always considerably and significantly higher. I am not alone in this.

That's interesting. I'm borderline prediabetic/diabetic - as in, just one count lower, now, and I would be seen to have 'normal' blood sugar levels. I was overweight before I reduced my carbs, though, so suspect I wasn't 'healthy', whether or not at risk of diabetes.

Although I've been sticking with the Ascensia Contour One meter lately, out of interest today I also used the Aviva again - mostly because the measure of 5.3 mmol/l struck me as quite low on the Contour. The Aviva measured it as just the same this time! Seems odd to me, how those two meters can produce utterly different results and then identical results. Still a bit puzzled, overall...

 

[DianaMC]

If there is a huge difference, or a very high (or low) reading that is unexpected, my suggestion is to re-test with the same meter. They all throw out rogue readings from time to time, and bringing spare meters into play muddies the waters.

Thanks for that suggestion @Bluetit1802 - Interesting about the rogue readings! I didn't realise that.

 

[Bluetit1802]

Thanks for that suggestion @Bluetit1802 - Interesting about the rogue readings! I didn't realise that.

Meters only need to conform to the required accuracy 95% of the time. The other 5% they may conform, or they may not. There is always human error and there can be the odd corrupt strip.

 

[Major Buckmaster]

Hi, @DianaMC and @Rustytypin , thought I'd pitch in with a few comments on bg testing and meter accuracy.

There's two ways of looking at this.

The first way is to look at technical studies comparing various meters and see how they measure up according to industry standard tests.

For example, there's a fairly recent one, linked to in this article:

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

Contour Next comes out on top as being the most accurate.

You've both mentioned that meter, and, if that was how you choose to judge it, that should be be your preferred meter.

But the other way of looking at it is this: the technical differences between all the main contenders are just that: technical differences.

In the real world, the plain truth is that no meter is really all that accurate.

All of them, no matter how fancy their marketing is, or where they are placed in technical tests, just provide broad indications of general ranges.

They are accurate enough for that purpose. I'm T1, so am looking at it from a slightly different perspective.

I'm broadly interested in knowing whether I'm sub-4, between 4 to 7, or above 9.

If I see 5.3 on the meter, and test again at 5.8, or even 6.2 or whatever, those will all be the same number to me: I'll read it as "about 5 to 6", which is good enough for my purposes, as, even though I don't know for sure where it lies after the decimal point, it doesn't matter, because I can be reasonably certain it isn't 3 and it isn't 8.

I use that approach in my T1 world. Meters don't get any more accurate when used by T2s, pre-diabetics, LADAs, or whatever: meters are meters whoever is using them.

Sorry, been waffling on a bit, the point I'm trying to make is that the decimal point accuracy which many newbies look for in bg measuring simply doesn't exist with the current technology, the best you're going to get is a broad range indication, which is actually good enough for most purposes.

I've seen posts from people who've driven themselves mad seeking an accuracy which just doesn't exist in this field.

Learn how to read them for what they are: broad indicators. Near enough is good enough. They are still very useful, despite their limitations.

So the contour next is the best meter?

I want to get a new meter. I am always reading in low to high 5s yet my hba1c was averaging 7. I’m not convinced of it. But I don’t trust my meter either so is this the one I should get??