# Phone scanning Libre vs Reader scanning Libre



## Lily123 (Feb 14, 2022)

I know there’s only a difference of 0.2 but these were taken within the same minute so how are they reading differently?


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## Loobyloo (Feb 14, 2022)

I would be happy with that mine is at worst 5.2 on libre and 8.6 on meter. Customer services said  1-2mmols differerence is acceptable (They are sending me replacement sensor). So what you have is very close.


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## Lily123 (Feb 14, 2022)

Loobyloo said:


> I would be happy with that mine is at worst 5.2 on libre and 8.6 on meter. Customer services said  1-2mmols differerence is acceptable. So what you have is very close.


What I put must have been confusing. I meant that the reader for the libre (scanning the sensor) read 0.2 lower than my phone scanning the libre sensor within the same minute


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## Loobyloo (Feb 14, 2022)

Ah sorry misunderstood. My BG tester can read different on every jab so i suppose these are the same. None claim to be 100% accurate.


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## Proud to be erratic (Feb 14, 2022)

Lily123 said:


> I know there’s only a difference of 0.2 but these were taken within the same minute so how are they reading differently?
> View attachment 20090
> View attachment 20091


If I got that I'd be content. The difference of 0.2 is wholly within the accuracy of the 2 devices, your reader and your iPhone. In real terms you can round the number down to 6 for both. When you consider the estimating that is routinely in an accurate carb count, there is no point in getting concerned over such a small difference.

Incidentally, I remember you saying in the "which pump" thread that you were going to weigh your cereal the previous evening, so you can get ahead of morning timings. One easy way to get a standard weighed amount of cereal is to use a volume measure. Decide what weight you want, then find a cup/ glass/ small bowl /small jug or any other container that holds exactly that weight - when full to exactly level. No heaping! Then every morning just use that container as your measure for your pre- weighed amount. Its quick and very "repeatable". Also works particularly well for liquids, eg milk. You can't overfill a container with a liquid.


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## Lily123 (Feb 14, 2022)

Proud to be erratic said:


> If I got that I'd be content. The difference of 0.2 is wholly within the accuracy of the 2 devices, your reader and your iPhone. In real terms you can round the number down to 6 for both. When you consider the estimating that is routinely in an accurate carb count, there is no point in getting concerned over such a small difference.
> 
> Incidentally, I remember you saying in the "which pump" thread that you were going to weigh your cereal the previous evening, so you can get ahead of morning timings. One easy way to get a standard weighed amount of cereal is to use a volume measure. Decide what weight you want, then find a cup/ glass/ small bowl /small jug or any other container that holds exactly that weight - when full to exactly level. No heaping! Then every morning just use that container as your measure for your pre- weighed amount. Its quick and very "repeatable". Also works particularly well for liquids, eg milk. You can't overfill a container with a liquid.


I thought the Libre took a reading a minute and then scanning twice within the same minute would get the same result? I must be confused with something else. 

That is a good idea to try with the cereal but I’ve stopped eating cereal in exchange for yogurt and a Nature Valley bar  (not enough time to get everything done in the morning, I wake up at ten to seven) If I do go back to cereal I will definitely use that for weight.


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## rayray119 (Feb 14, 2022)

Loobyloo said:


> I would be happy with that mine is at worst 5.2 on libre and 8.6 on meter. Customer services said  1-2mmols differerence is acceptable (They are sending me replacement sensor). So what you have is very close.


To be being 2 out is a bit to much for me I can deal with it being 1 out but I don't like the idea of something saying 5.4 for example when it couldbe 3.4


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## Lily123 (Feb 14, 2022)

rayray119 said:


> To be being 2 out is a bit to much for me I can deal with it being 1 out but I don't like the idea of something saying 5.4 for example when it couldbe 3.4


Libre is calibrated to normal levels (I’m not sure what levels are regarded as normal in this sense) so the Libre might read higher at high numbers and lower at low numbers


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## Pattidevans (Feb 14, 2022)

rayray119 said:


> To be being 2 out is a bit to much for me I can deal with it being 1 out but I don't like the idea of something saying 5.4 for example when it couldbe 3.4


I think Lily is talking about 0.2 not 2mmol out.


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## Lily123 (Feb 14, 2022)

Pattidevans said:


> I think Lily is talking about 0.2 not 2mmol out.


I didn’t mean by a finger prick compared to Libre , I meant my phone and the reader both scanning the Libre within the same minute giving slightly different results. Yes I meant 0.2


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## rayray119 (Feb 14, 2022)

Pattidevans said:


> I think Lily is talking about 0.2 not 2mmol out.


Yes sorry I know proberry shouldn't have interumpted


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## Lily123 (Feb 14, 2022)

rayray119 said:


> Yes sorry I know proberry shouldn't have interumpted


Nothing to be sorry for


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## Lily123 (Feb 14, 2022)

Benny G said:


> Hi @Lily123, I'm not sure if anyone else is following what you are saying, but I am. You are using the official Libre reader to scan your Libre sensor, and also scanning the same Libre sensor using the Libre app on your phone. They are showing a difference of 0.2
> My best guess is that the algorithm used in the scanner device is older than the algorithm used in the app on your phone. Abbott are now concentrating on the phone app, and currently have no plans to release a scanner for Libre 3. So, further firmware updates for the Official scanner may or may not happen, but the software for your phone will be updated as required.


That was my thinking - that they were using slightly different algorithms but a difference of 0.2 isn’t that major it did confuse me


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## Lily123 (Feb 14, 2022)

Benny G said:


> The data received by both devices from the sensor is exactly the same, the algorithms interpret slightly differently, trying to reduce the lag that we notice when we compare against finger pricking. I assume the phone app should be doing a better job, most of the time.
> The way to check if it is to reduce the lag, is to do the same comparison when your glucose level is dead flat. The values should be the same.


Yes I did scan again and both said 6.2 and stable


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## Lily123 (Feb 14, 2022)

Benny G said:


> Good.
> 
> I use the Libre app on my phone, side by side with the xDrip app. It's the same data going through both programs but different algorithms and in the case of xDrip calibrations to interpret that data. So, quite similar to your situation.


I have an iPhone so can’t use xDrip - I normally don’t use the reader but fancied a change and the alarms are less of an  annoying sound on the reader


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## Lily123 (Feb 14, 2022)

Benny G said:


> I wasn't pushing xDrip, I just used it as an example


I know, it would be helpful for something like xDrip for iPhones or for xDrip to work on iPhones as calibrating the Libre would be helpful


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## helli (Feb 14, 2022)

Lily123 said:


> I know, it would be helpful for something like xDrip for iPhones or for xDrip to work on iPhones as calibrating the Libre would be helpful


There is a xDrip for iPhones. I think it is called xDrip4iOS. 
i am afraid that, beyond the name, I know very little about it.


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## Lily123 (Feb 14, 2022)

helli said:


> There is a xDrip for iPhones. I think it is called xDrip4iOS.
> i am afraid that, beyond the name, I know very little about it.


Ah, I may have to do some research about that


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## Proud to be erratic (Feb 15, 2022)

Lily123 said:


> I thought the Libre took a reading a minute and then scanning twice within the same minute would get the same result? I must be confused with something else.


No, I don't think you are confused. Although you are taking readings within 1 minute, perhaps within 20 seconds, you don't know whether the first reading was within  the previous minute for the sensor and the second reading was from the next minute for the sensor! 
When does sensor time start??? This philosophical (and unanswerable) question could become a great time waster!


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## rayray119 (Feb 15, 2022)

Proud to be erratic said:


> No, I don't think you are confused. Although you are taking readings within 1 minute, perhaps within 20 seconds, you don't know whether the first reading was within  the previous minute for the sensor and the second reading was from the next minute for the sensor!
> When does sensor time start??? This philosophical (and unanswerable) question could become a great time waster!


I thought it was every 5 minutes not every minute?


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## Sally71 (Feb 15, 2022)

rayray119 said:


> I thought it was every 5 minutes not every minute?


Dexcom takes a reading every 5 minutes, I think Libre might be every one minute


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## rayray119 (Feb 15, 2022)

Sally71 said:


> Dexcom takes a reading every 5 minutes, I think Libre might be every one minute


Libre 3 is every minute apartellty libre 2 Is every 5 mintutes


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## Proud to be erratic (Feb 15, 2022)

Lily123 said:


> Libre is calibrated to normal levels (I’m not sure what levels are regarded as normal in this sense) so the Libre might read higher at high numbers and lower at low numbers


I recently asked in a thread what does Abbott mean by "in range" (ie normal) low and high levels and @everydayupsanddowns provided a link to an International Symposium where, after due research and various learned papers, the Symposium agreed normal was 4-10 for adults. I have assumed that Abbott have adopted that range, but I can't find anything that absolutely definitively confirms this is what Abbott means by 'normal'.

To be strictly accurate it would be 3.9-10, since these numbers are in mmol/L and the Symposium used both US units as well as European, which convert at 18:1, ie 3.9 x 18=70 and 10x 18=180 with the US range being 70-180mg/dl. The nos 70 and 180 are, without doubt, a rounding off of the original figures calculated to several decimal places. It is so much simpler for us to just adopt the round number of 4.
The Symposium was looking at aspects of diabetes clinical care when using new technology such as CGMs and how to interpret the data from this new technology. Their start point was to agree what is 'normal' or 'in range'.


rayray119 said:


> I thought it was every 5 minutes not every minute?


No, Libre 2 is broadcasting readings every minute (at least - there could be more going on within the sensor that we are unaware of). Those readings are being transmitted by Bluetooth and there are apps that can catch those readings and convert them to CGM. In practical terms keeping up with changes every minute is too onerous to be sensible and needs at least a 5 fold increase in data storage,  before interpreting that increased data. So most apps use 5 minute intervals, which is still up to 288 readings per day and effectively continuous.


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## rayray119 (Feb 15, 2022)

Proud to be erratic said:


> I recently asked in a thread what does Abbott mean by "in range" (ie normal) low and high levels and @everydayupsanddowns provided a link to an International Symposium where, after due research and various learned papers, the Symposium agreed normal was 4-10 for adults. I have assumed that Abbott have adopted that range, but I can't find anything that absolutely definitively confirms this is what Abbott means by 'normal'.
> 
> To be strictly accurate it would be 3.9-10, since these numbers are in mmol/L and the Symposium used both US units as well as European, which convert at 18:1, ie 3.9 x 18=70 and 10x 18=180 with the US range being 70-180mg/dl. The nos 70 and 180 are, without doubt, a rounding off of the original figures calculated to several decimal places. It is so much simpler for us to just adopt the round number of 4.
> The Symposium was looking at aspects of diabetes clinical care when using new technology such as CGMs and how to interpret the data from this new technology. Their start point was to agree what is 'normal' or 'in range'.
> ...


That's confusing because albbort say every 5 minutes


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## Lily123 (Feb 15, 2022)

Proud to be erratic said:


> No, I don't think you are confused. Although you are taking readings within 1 minute, perhaps within 20 seconds, you don't know whether the first reading was within  the previous minute for the sensor and the second reading was from the next minute for the sensor!
> When does sensor time start??? This philosophical (and unanswerable) question could become a great time waster!


I forgot the timing from when I originally scanned the Libre to start the sensor made a difference , I assumed that it would be from the start of every minute and not possibly half way through the minute! 

Sorry if that makes no sense


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## Proud to be erratic (Feb 15, 2022)

Lily123 said:


> I forgot the timing from when I originally scanned the Libre to start the sensor made a difference , I assumed that it would be from the start of every minute and not possibly half way through the minute!
> 
> Sorry if that makes no sense


Makes perfect sense; your full minute could be out of step with the sensor's full minute.


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## Proud to be erratic (Feb 15, 2022)

rayray119 said:


> That's confusing because albbort say every 5 minutes


If you could kindly tell me where you found that I'd be pleased to look further. I'm very confident that it is generating output every minute because, when I'm closely monitoring from Diabox my BG while close to hypo, I switch from 5 mins to 1 min and watch the change of direction from down to up. This is one of the ways I stop myself from over-reacting and taking too much glucose with a consequent rebound into hyper.


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## rayray119 (Feb 18, 2022)

Proud to be erratic said:


> If you could kindly tell me where you found that I'd be pleased to look further. I'm very confident that it is generating output every minute because, when I'm closely monitoring from Diabox my BG while close to hypo, I switch from 5 mins to 1 min and watch the change of direction from down to up. This is one of the ways I stop myself from over-reacting and taking too much glucose with a consequent rebound into hyper.


maybe its just the offically libre app and reader then.  because I thought that was the big thing they were making about libre 3 being every mintute


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## Proud to be erratic (Feb 18, 2022)

rayray119 said:


> maybe its just the offically libre app and reader then.  because I thought that was the big thing they were making about libre 3 being every mintute


I think the "big thing" about Libre 3 is that it will provide continous output rather than flash or scanning, to get your readings. A 2nd aspect is that the sensor is smaller. In reality this is just Freestyle catching up with other sensors by providing CGM which some others already do, in what seems to be a growing market. Growing in the sense of other providers and growing in the sense that the technology exists and providers need to keep up; there is market demand and the more it is publicised (not least on this forum) the more that demand will be - world wide.


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## rayray119 (Feb 18, 2022)

Proud to be erratic said:


> I think the "big thing" about Libre 3 is that it will provide continous output rather than flash or scanning, to get your readings. A 2nd aspect is that the sensor is smaller. In reality this is just Freestyle catching up with other sensors by providing CGM which some others already do, in what seems to be a growing market. Growing in the sense of other providers and growing in the sense that the technology exists and providers need to keep up; there is market demand and the more it is publicised (not least on this forum) the more that demand will be - world wide.


they were also ateritsing that it was ever minute compared to every 5 minutes though. i know cgm is the main thing but they seemed to be using that as another big atertising point.


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## Proud to be erratic (Feb 18, 2022)

Well, I haven't seen that and I know for certain that Libre 2 is already generating a continuous (minute by minute) output. Let's move on.


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## rayray119 (Feb 18, 2022)

yes sorry i guess that the hacks


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## mikeyB (Feb 18, 2022)

I wouldn’t be in the least surprised at such a minor difference - ypu can get that with two fingerpricks using different fingers.

What you should be worried about is being 6.6 (0r 6.4) with a directly down arrow means that you are dropping quickly. Eat a couple of JBs is what I’d do with that.


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## Lily123 (Feb 18, 2022)

mikeyB said:


> I wouldn’t be in the least surprised at such a minor difference - ypu can get that with two fingerpricks using different fingers.
> 
> What you should be worried about is being 6.6 (0r 6.4) with a directly down arrow means that you are dropping quickly. Eat a couple of JBs is what I’d do with that.


Thanks


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## Brava210 (Feb 21, 2022)

You can use CGM on the Libre 2 with Diabox, which will read the sensor every 1 or 5 minute interval


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