Libre 2 reader and phone app


I’m newly diagnosed and started with a libre 2 2 weeks ago - started it with my iphone because the reader was delivered later… i was not able to add the reader later and some literature said, if started on phone it cant be added to the reader, but if started on the reader, the iphone can be synced later… So, when replacing the sensor today, i started it with the reader instead and now it can’t be read on the phone. Is there a way to unpair or change device? or am i stuck with the extra device until the next sensor? Is there a way to sync up all the data?


Hi @pady87 . I don’t use Freestyle, but typically with these devices you can only use one item as a receiver at a time - either the one that came with the device, or your phone.
I would think you could unpair it from your phone to use with the device receiver instead. Freestyle tech support should be able to walk you through the process to use the device as receiver but transmit readings to your phone where it might be more convenient and discrete to see your numbers.

As far as I know, each time you start a new sensor you have to pick either the reader or your phone and you can’t use both at the same time. The data should all be going to the same place, though, if you’re signed up with LibreView ( You might need to manually upload the data from the reader; I can’t remember if Libre 2 does it automatically or not.

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@bsteingard is right, the Libre 2 is one receiver, phone with app or reader, at a time.
Libre2 manual pages 43 and 45.

There isn’t a way to make the reader data show up on your phone. The Abbott LibreView web site lets you upload data from the reader and offers better reports than the phone app.

Since we are talking about the Libre, if you have the bandwidth left to consider another recommendation, the Dexcom G6 or G7 CGM gives closer to real numbers more often than the Libres. The Libre 2 is absolutely a great choice by your doc to get you on a CGM immediately. Either way when you are ready let us know and we’ll help you with understanding what the CGM can tell you.

Yes, that’s right, the 3rd number one worst diabetes complication is having to understand all that math you didn’t think you would ever use in real life. :grinning:

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That is really strange! I have the Libre 14 day and I start it with the handheld reader and then the app on my phone. I can use both!

@homeschoolingmomof5 ya… looks like the libre14 day app allows that, but not libre2 for an odd reason… the reader doesn’t tell on me to my partner like the phone app, but that’s not really as convenient as I thought…

Yes… I am a math nerd, so the numbers are keeping it interesting at least for now… the libre2 itself was a sea change from finger pricks… it is particularly helpful to understand the impact of my activities on the glucose levels… I read a bit about the dexcom but heard g6 is better if I want to try a pump like omnipod 5… any further thoughts or things to consider are still appreciated!!

Note: When I started this I missed that Abbott came out with the Libre2 Plus (15 day). I’m referencing the Libre2 (14 day) data, the Plus data is in the same manual, add 30 to the page numbers.

In that link to the Libre 2 manual I posted earlier, on page 197 starts the statement of accuracy. Note that nowhere is a nice simple statistic that says the Libre 2 glucose measurement is +/- some percent of your actual blood glucose. The most important thing to know about all the currently available CGMs is they estimate blood glucose values by attempting to measure glucose in your interstitial fluid.

Table 1d is a good summary of the Libre2’s performance. Table 3c uses smaller bins.

So in the test group, when the participants BG was 80-120 71.7% of the Libre 2 readings were also 80-120, 18.8% of the Libre2 readings were between 61-80.

This tells us that

  • We still need a good working glucose meter and test strips.
  • Libre 2 readings, if they are wrong, are more likely to lower than actual
  • The CGM can be wrong without being defective.
  • We need to pay attention to how we are feeling.

The numbers might look bad but when you consider your doctor’s instructions for dosing insulin it becomes close enough.

From my personal experience with the Libre and Libre 14 day (never tried the Libre2) before I changed to Dexcom in 2021

  • The Libre was fine when my glucose was steady. When the change was greater than 4 mg/dL per 15 minutes it was in the ballpark but never close.
  • The Libre takes an hour to register increasing glucose values after treating for a low.
  • I think the raw Libre sensor values are very noisy so the estimated glucose values we see are from an algorithm based on a best fit line.
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Thanks so much for this - I’m starting to understand my libre 2 better. I agree it does not like ups and downs and i’ve learned to verify with either finger pricks or how i’m feeling at those times.