Finally got my CGM (continusous glucose monitoring) up and running!

After, quite literally, a year of my doctor writing the script to get the Libre with the 14 day sensors, I got the device and have it working.

It appears I have the Libre2; I am in the USA.

I have a few questions I was hoping the community could help me with:

  1. It seems that the sensor records levels every 15 minutes automatically and stores them. Is there any limits to this? (for example, the memory bank only holds 8 hours, etc).

  2. I have an android phone. Diabetes M won’t read my device, but DiaBox does. Is there any advantage to using the 3rd party apps versus using the offical libre app?

  3. I am able to download my data into a .csv file by uploading it from the device to the LibreView website. Why should I use something like Tidepool?

  4. What exactly is nightscout supposed to do with my sensor?

  5. Is there any other hacks I am missing?

The Libre1 starts overwriting older measurements if you don’t sync for 8 hours. I sure hope they fixed that in the Libre2; what does the manual say?

Regarding alternative apps: If all you need is an app that can scan the device, capture notes, and that lets you export your data, the official app seems like the way to go. If you need to manage your blood sugar in real time (incl dosing insulin), other apps have more bells and whistles to help with that. Tidepool lets you “donate” your data for research, but maybe you can still do so by uploading the LibreView .csv…

Not really a hack, but a common mistake is to not discard instant readings when looking at historic data. Instant readings are extrapolated, and often way off. Other than that, see my project log :smile:

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Thanks @ejain. Upon checking the manual, it looks like the libre2 stores 8 hours of data and then starts deleting.

Thanks for letting me know about the instant readings. I can see in the .csv file how to remove those.

My latest “issue” witht he sensor is it I am not sure its reading correct so I have ordered some blood test strips to verify it. My sugar hasn’t gone above 112 in the last 24 hours and doesnt seem to respond to meals at all. I even went on a 50 mile bike ride and it pretty much stays flat as a pancake. I guess that could be good but I have to do more research to understand the data. I would’ve expected more of a transient after eating based on reading reports of other healthy people.

Maybe drink a jug of apple juice? If that doesn’t get your blood sugar up, that’s suspicious…

I got my first results back. This is pretty cool! My levels seem okay.

Sorry for the rather late response, did you work out why the readings were so constant?

Some of the sensors can be faulty, which may be what you were seeing.

afaiu the sensors read every minute, but only store a value every 15 minutes.

I used the Libre app for a long while, but then bought a Miaomiao (which you attach to the sensor on your arm and which scans it every 5 min) so I could get hypo warnings at night using the Nightscout XDrip+ app ( I don’t use a pump, but the data is still useful for self administered pen insulin, and there’s more to be done re data gathering and analysis :grinning:

One interesting aside is that since starting this recently and going back to doing more finger prick blood tests for calibration purposes, I’ve realised that the Libre reads low (apparently to avoid you going low), which isn’t ideal for long term complications.

Hi Simon,

The Libre reads low? LIke about how much lower?

 - Eric


@ejain: Here, though it may be that this is referring to the libre2. I’ve not dug very far into it:

@ericbalkan: I see similar results to the ones shown here:

I can plot and upload a graph to compare if you’re interested,



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fwiw I’ve just changed sensor and both the Libre app and XDrip+ with calibration read almost identically (the previous two read significantly lower). There’s obviously some variability. I believe if there’s too much then Abbott will exchange the sensor (and take the old one back to check), which they did with the first sensor I was using with XDrip+.

I’ve also spoken to another diabetic I know on the school run and her experience, using XDrip+ for much longer than me, is that some read high, some read low and some read dead-on. YMMV!

I use a Medtronic Guardian 3 CGM. I was taught the CGM measures glucose in the interstitial fluid and will almost always be slightly different than a finger stick measuring blood.