Freestyle Libre and Blucon as CGM



Earlier this year I pre-ordered a Blucon Nightrider from Ambrosia Systems (https://www.ambrosiasys.com/). This is the reusable device that sits on top of the freestyle libre. Well, a few months ago I started on a minimed 630g with Enlite sensors and forgot about the Blucon until it arrived a few weeks ago. I happened to come across a couple of unused Freestyle Libre sensors during my seasonal cleaning so I thought I would give the system a try.

The blucon itself is about as thick as a pen and takes a standard watch battery:

It needs something to hold it over the sensor so I just stuck a grifgrip over it. It kind of bulges out when added to the thickness of the sensor.

The nightrider is not waterproof but with the grifgrip I’ve showered with it and it seems to work fine. I don’t have it covered well enough to go swimming with it.

There is an app to download and I have an Android phone so I can’t comment on the iOS version. After starting the app you have to pair the phone and the device. To reset the blucon device and make it pair you have to get a pin and push into the tiny hole on the top. A light blinks red indicating it was pushed. Then you tell the app to scan for a device. This tripped me up a little because it found my device but then got stuck waiting for data. There wasn’t a notification it successfully paired and it went straight into reading from the sensor, which wasn’t attached at this point.

I activated the sensor with the Libre reader and then the Blucon. I was a little surprised the blucon started getting readings right away while the reader made me wait for the 1 hour warmup period. So that was the first giveaway that the Blucon is reading raw numbers and does its own interpolation/analysis of interstitial glucose readings that is different from the Libre reader.

The app gets readings every 5 minutes. Here is a comparison between the app, my meter, and the libre reader:

The Ambrosia App is the lowest, when I tested it said I was at 91. The libre reader said 113 and my meter said 122. The app seems pretty consistently lower than my meter and libre reader. I’m sure there are many factors that go into the calculation ranging from the particular sensor to whatever so this may not generalize to others.

You might notice the Y axis scale on the Ambrosia app. It auto-scales based on readings. So if in the time period selected I had readings from 80 to 100 then the scale will be about 80-100 and it might look like giant peaks. I suppose this is nice sometimes for fine detail but it would be nice to be able to change the Y axis scale because generally I want to know if I’m high/low/medium and I have to think a little more by also checking the scale of the Y axis. Right now you can’t change it the Y axis scale in the app.

The trends mostly seem to match, although as I’m typing this my meter says I’m at 213, the reader says 194 with an up arrow, and the Ambrosia app is at 137 with just a slight tick up. So the app definitely seems to lag behind in terms of numbers, maybe by 15 minutes or so.

Here is one it did catch, the tallest peak below was when I got up at 7am to put the trash out (there have been bears roaming around trash diving so we can’t put it out too early) and I ate a donut hole and the app did show a 30 point rise, although I was closer to 100 to start with rather than 75.

My major criticism is the app is missing a lot of features. Want to register to share numbers? Coming Soon! Add a note? Coming Soon! Change any settings other than units? Can’t do it. The pairing process didn’t clearly indicate it had successfully paired. The biggest issue is there are no alerts in the app, which I think is the major reason you’d want a CGM, to alert you if you are low or high. I’m a little surprised this is currently missing since that doesn’t seem like a terribly difficult thing to add.

The app also chews up some battery life on my phone, although I haven’t used it enough to quantify it yet aside from it seems like my battery is draining a little faster than usual.

My feeling is in its current state all the Blucon does is save you the little bit of effort it take to swipe the reader over it. But once the other features are added, especially the alerts, it could be a pretty nice CGM alternative for a self-funded CGM at a reasonable cost. Actually, a one-time cost for the Nightrider! How often do you see one time costs for diabetes tech!

Since the blucon reader appears independent of the Libre reader it might even work with the freestyle libre pro. This was alluded to in other thread, but that should be a moot point when the Libre makes it to the US market (maybe around the end of the year).

You can use the Freestyle Libre Pro as a real CGM with no alarms
Freestyle Libre, $45, shipped worldwide
Switching from Dexcom G5 to Freestyle Libre
Abbott Freestyle Libre now approved in the US

Thank you for posting this! A couple of weeks ago we were talking about the Blucon and wondering how well it works. So this is very useful information!


You’re welcome! In the thread you posted there was the question of if the Blucon app could be automated with something like iftt. Unfortunately it doesn’t appear to be. I checked to see if it might implement a tasker plugin or similar but it doesn’t seem so.

When the share feature is completed then it should be possible to also add alerts, on the chance that sharing is implemented before alerts.

One other item to add I forgot to add, there is no history if the phone app isn’t there to receive data. The libre reader will read the past 8 hours of data values on a scan, but if the phone isn’t receiving when values are sent then they are just lost.

Anyway, the way to go to get an alertable CGM on a libre at the moment seems to be the Nightscout / Glimp approach on something like the sony watch stuck on top (although even bulkier than the Nightscout).


@kenrick, I had missed your thread when it appeared as I was away for a couple of weeks. This was a GREAT post!

I wonder – have you experimented further? How do you feel about accuracy vs the Dexcom, after a few weeks of experience? Has more functionality appeared in the app? The alarms, in particular?


Thanks for posting this! The Libre just got approved in Canada. My insurance refuses to cover a CGM, so I’m paying for my Dexcom out of pocket. If I have to pay for the Libre out of pocket it will end up costing me more because of the inability to use a sensor for more than 14 days. But I’m really hoping that my insurance will cover it as a glucose meter, as I’ve heard some people getting it covered this way. If my insurance covers it, I’ll be getting it. I was planning on still using the Dexcom intermittently during high-risk times (such as when travelling) because I do find the alerts extremely valuable. I could remember to swipe often during the day, but not while I sleep, obviously. But if this Blucon and app have the ability to alert at that point, then it’s very possible that I can use this device with it. It would also be great if it would work with an Apple Watch, as that will probably be my next big purchase at some point.


Thanks! It still doesn’t have alarms or sharing functionality. I saw a tweet from the company last week that said alarms were “coming soon”. I haven’t experimented further, but did check for an app update (there wasn’t one). I don’t have a Dexcom for comparison, but do have an Enlite. I’d say the Dexcom/Enlite functionality and the algorithms to predict BG from interstitial fluid are much better – the blucon app readings lag behind, it seems like right now they are basically raw data with some smoothing.

I actually got a little frustrated after a week and took the nightrider off. It just wasn’t adding value and the extra bulk was a little uncomfortable. The next day I was hiking in the mountains and the reader said the sensor was too cold to read! It wasn’t that cold but the windchill must have gotten to it. I started rubbing the sensor to warm it up and ended up ripping it off :frowning:

There’s a lot of room for improvement, and it’s mostly on the software end, so improvements should come quickly. The next year or so should get interesting! Also, with Bigfoot partnering with Abbott, if they make a real artificial pancreas product that could make a splash.


Not if the software requires FDA approval. Nothing that requires FDA approval comes quickly. That is one of the problems with the Dexcom. It takes them a year or more just to get approval to tweak an algorithm, change the screen background, or make any even minor improvement.

New FDA program pre-approves tech to speed medical progress

@kenrick, THIS is exactly why I love this forum – the experimental testing from others gives invaluable information that cannot be obtained any other way. This is great info.

I agree – this is interesting. BigFoot has not been very active in patient activities though – I am not sure if they will ever come out with anything. I hope they do!


Oh, great point – I assume that is likely their hold up, since from a programming perspective it is such a simple thing to add alerts.


Thank you for this report.
I got some interesting news.
xDrip+ is now able to connect to the Bluecon.
So you will have Alarms, Calibrations, monitoring at a smartwatch and so on.
As I got this news, I ordered one.

Many thanks to the developers of xDrip+!!!


Here is the Bluecon video btw:


Have the blucon since about 2 or 3 weeks.
Using it with xdrip+.
This is a really good kombination!


2 posts were split to a new topic: New FDA program pre-approves technologies to accelerate medical progress

New FDA program pre-approves tech to speed medical progress

In the meantime there where some additional news.
Freestyle Libre (not only the pro) is available in us.

The best news are that xDrip+ has full support for the blucon!!!
My new setup is now:

  • Android Smartphone with xdrip+
  • blucon
  • pebble
    The battery of the blucon is good for about 3 to 4 weeks. Much better than using Sony smartwatch and librealarm as collector.

xDrip also can sync to follower’s without nightscout. Direct xdrip master to xDrip followers!


@jroth Bringing xDrip+ functionality to the Libre with something as easy and functional as Blucon could be a game changer as far as acceptance of the Libre in the U.S.

Have you ever used the Dexcom G5? If so, how would you compare the Libre as a CGM with the G5?

I follow xDrip+ pretty closely and a large part of their user group is in Europe and are Libre users primarily because of the cost and lack of availability of the Dexcom. But I haven’t seen many first person comparisons of the two systems.


I only tested the old dexcom for 1 week in a clinic.
So I can’t compare. The costs are different. Because of that the german health issurance is paying for libre for many peple. They pay only for cgm like dexcom if you can’t feel low bg / hypo.
Using xdrip, you are able to calibrate. With this fact, you will get very real bg values campairing to the blood test. It’s also important at both system, that you calibrate in a stable bg time.
IMHO ots fact, that libre fgm with blucon and xDrip has the same functionality like a cgm.
Some insulin pump are supporting cgm.
You don’t have this with libre, exempt you use a closed loop using androidaps.
Closed loop is a separate Thema…
Very useful is the master / follower design of xDrip without nightscout.

Please be patient with my bad English.
Hope my comment is helpful.

Greetings Jürgen


Du sprichst sehr gut!


Sometimes I’m not sure. So I think it’s important to tell the people that I’m a foreign. So it will be easier to understand and have more understanding.


@jroth Your English is not bad at all! In fact you speak much better English than I speak German :blush:.

And your comments are always helpful!

My curiosity about the Libre with blucon is that in not too many years (months?) I will be retiring or slowing down and will be at the mercy of Medicare. With the cost difference between Dexcom and Libre it’s a possibility that Medicare will start covering the Libre instead of the Dexcom. I just want to be prepared for that possibility.


This thread has lots of good info on setting up the Libre with Blucon and xDrip+ as a CGM.
I am actually kind of jealous to get this functionality on ones smartphone!