Getting hypo alerts with libre, blucon and xDrip+

I like libre a lot, but, as other users will know, the factory calibration can be a bit iffy at times, and there's no hypo/hyper alerts.

However, a few weeks ago, xDrip+ was modified so that it will collect data from Ambrosia System's Blucon Nightrider transmitter.

The Blucon gets placed on top of the libre sensor, then it bluetooths readings every 5 minutes to xDrip+.

That means you can use xDrip+'s various features to calibrate against bg tests, set up hypo/hyper alerts, get predicted low warnings and a whole stack of other things.

I've been using it for a week now, been bg testing a lot more than usual to get a sense of whether I trust it's readings against blood. Have to say I'm pretty impressed with it so far. Being able to calibrate removes a lot of the uncertainties of libre and the alerts are great.

Blucon is a one-off cost of just over £100, runs off a replaceable watch battery, isn't waterproof so needs to be tagged onto the sensor with a plaster to allow removal for showers. The makers say it's warranted for a year but I suspect it'll last longer - it's just a circuit board and nfc reader so I'm not sure there's anything there to wear out. There's a £20 import tax in UK but there's a post somewhere on their facebook page about a way to reclaim that.

xDrip+ is free open source software which is covered by disclaimers saying it's a "use at own risk" gig, but it's used regularly by dexcommers and seems to be widely acknowledged as reliable.

All in all, it's a cheap and cheerful way of getting alerts with libre, so thought I'd mention it for anyone interested in getting alerts without going full dexcom or haven't the technical skills to build limiTTer etc. Not dissing dexcom in any way, I'm sure it's a wonderful product, but for various reasons I decided I didn't want to use it.

Here's a few links for anyone interested in this route:

Blucon can be bought here:
https://www.ambrosiasys.com/

https://m.facebook.com/ambrosiasys/?locale2=en_GB

xDrip+ can be downloaded here:
https://github.com/NightscoutFoundation/xDrip/releases

Diabeticliberty said:

Thank you ever so much for your post

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Aw, cheers!

I've only been using it for a week and don't pretend to have any expertise at all in the ins and outs of calibration (and I might decide in two weeks time that it's a piece of junk!), but this is my take on it so far:

Setting it up:
Setting up the blucon is easy. You put a CR2032 battery in it (pack of six for a few quid or so from any shop which sells camera, watch batteries) and push a cocktail stick in the on-off hole till it blinks red.

Install xDrip+ to your phone. Mine's is a 99 quid LG K8 android. Open it up, then click the menu button at top left (the three horizontal lines) then in Settings/Hardware Data Source, select "Libre Bluetooth". Then scroll back to the main menu, click again and select "Bluetooth Scan". From the screen that opens, click "scan" at top right. Wait a while and you should hopefully see BLUxxxxx listed as a found bluetooth device (xxxxx will be a series of numbers). That'll be xDrip+ saying it's found your blucon. If you get nada, try stabbing the blucon with the cocktail stick again till it flashes red, then do the 'scan' routine again. Once you eventually get BLUxxxxx showing, click that entry, it'll then bring up an input screen where you need to type in the last 6 numbers printed on the side of your specific blucon. That'll pair blucon and xdrip so they can talk to each other. There's then a screen comes up which asks you to input a couple of meter readings, then there's a bit of waiting while it gets a few values from the sensor. If it's worked, after about 10 minutes, you should be able to go the home screen and see a pretty little graph with some blue dots on it. You'll get another blue dot every 5 mins.

Or at least, that's how it worked when I set mine up....it might have changed since then.

You need to play about with it enough till you get the System Status screen says it's connected like this:



Calibration
I'm just a casual user of cgm, don't pretend to have any expertise in it, so this is merely my take on it. Others who know more about it will hopefully steam in and correct me where I've misunderstood it.

Sensors break down glucose in interstitial fluid, measure electric current coming off that, and send a number to the interpreting app which then does some calcs to figure out what that number represents in terms of blood glucose. Because of the uncertainties/variables inherent in that process, Dexcom needs to be calibrated by bg test to tighten things up - sensor and algo say x, but it makes it more accurate to take some of the guesswork out by bg testing and telling it, you say x, but I'm telling you it's y, so re-do your sums.

Libre is meant to be factory calibrated to avoid that, but, err, it often doesn't and needs some help.

Can't do that with the current libre set up. But with xDrip+, what you do is do a bg test, then go to the main menu, select "Add Calibration", enter the bg reading. The graph will adjust to take account of that current, hopefully accurate bg test.

What I'm not sure about at the moment is how doing that with a factory calibrated sensor, which is then nfc'ing data to blucon, which is then bluetoothing to xdrip+ will work in practice - is data going to be lost, can libre work in that set-up, will accurate readings just be fluke? - lots of uncertainties at the moment.

Like I say, only been doing it for a week, so, all I'm saying at the moment is, yeah, it's doing ok at the moment, I've cautiously bolused from it a few times, but will keep it under review.

Calibration like this does nothing to the sensor at all. The sensor will send the same data it otherwise would. Whether it being sent via blucon changes it any, maybe there's an issue there - does it lose some packets of info, I don't know.The calibration occurs in the interpreting app, not the sensor. You're not recalibrating or changing the sensor - you're recalibrating what the receiving app does with the information received from the sensor.

Whether it'll sort out a totally duff sensor, I don't know.

xDrip+ has a calibration graph, like this:



Some of the dots on that are bang on the red line, some aren't. Other than knowing generally that it's best to calibrate when stable, I don't yet know enough to interpret that graph.

What I do know, though, is that in the following couple of screenshots, that's me getting woken up at 4am by xDrip+ ringing as I approached 4, taking 5g, going back to sleep and trotting along at 5 to 6 therafter, happily out of hypo zone. I tested at 4am, xdrip said 4.2, meter said 4.3... Yay, might have been hypo but wasn't.

Stefans said:

Scott-c, do you have to start a new sensor with the blue con, or can it in anyway work together with the freestyle reader?
looks very interesting, need to read up on Xdrip+, thanks a lot for the info.

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No, you don't need to start a sensor with blucon. Yes, it still works with the usual reader.

If you've got an active sensor up and running, and are scanning with the normal reader, you can carry on doing that, even if you put the blucon on top and get separate readings through blucon/xdrip+.

My current sensor had been running for a few days, was scanning it, then I put the blucon on top with a 7 by 8 plaster, so could scan with the reader when I felt like it, but was also getting the blucon readings pushed to xdrip on the phone. It's been useful to compare and contrast the two readings - xdrip seems to be ahead in terms of accuracy against meter at the moment compared to the reader!

Before the xdrip route became available, I was using blucon's app, linkblucon. It's rubbish, don't bother with it, but it was quite clear from that experience that if I wanted to plaster blucon on top of libre for a few days and get readings from both, I could do so and then just take it off and on again as I saw fit. So, there's a lot of flexibility in it. I can just use libre reader if I want to, and then pop blucon on top for a few days if I want alerts. They kinda co-exist, but because they use different algorithms, be prepared for different results.

Diabeticliberty said:

Really really interesting. The thing is if I buy one and end up killing a sensor by tinkering with it then it's only 1 sensor and undoubtedly worth the expense. The other possibility of course is that my Libre sensors which are hit and miss at the moment and unfortunately too much miss finally become trustworthy. WOW!!!!!!! You have given me much to consider. Thanks again

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You can attach the blucon to the sensor anytime you want in the 14 day lifetime of the sensor. So, if you're worried about breaking one, it's easy to wait until day 10 or 11 or whatever, so you're only experimenting with and potentially losing 3 or 4 days rather than the whole 14.

I've run a few sensors where blucons been on for 4 days, then sitting on the sideboard for 3 days, then back on for 2.

Diabeticliberty said:

All I want is accuracy. A lot more accuracy than I am currently paying for. Currently I am stuck between a rock and a hard place. The concept of Libre was absolutely revolutionary for me. Even with its many flaws and silly quirks I would not want to go back to pricking my fingers over 16 times per day. The thing I find though that even it's most ardent die hard advocates of which there are many, when questioned seem to have to endure some of the silly nonsense that I have to frequently go through with mine. I cling on to the hope of further developments with the next generation of flash monitor in the hope that we can all leave finger pricking behind us. For now though your own suggestion seems particularly appealing.

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Yes, it's tricky. Libre seems to work perfectly well for some people, yet not for others. I don't know why.

ps: when I was typing, "not for others", the autotype put it as, "not for otters". Going to have to catch one of those little critters next time I'm near a river and get it wired up to one to test that out...

GrantGam said:

Great post @Scott-C, I'm sure many Libre users will soon be giving this heavy consideration

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Cheers, Grant. It's a bit of a learning experience at the moment. Strips, yeah, I can do those, Libre, yeah, kinda got it figured out, xDrip+, whoah, sometimes it's just too much information!

PIPPO_PIPPI said:

Hi. I'm using xDrip+ with libre and blucon from three days, and I'm enthusiast, really. Libre sensors have a bit erratic calibration, so the possibility given by xDrip+ to calibrate "on the field" is really welcome, and works very well, at least with this sensor. But I have two stupid problems with the APP:
1- How the hell can I stop the LOW alarm when it starts?
2- I use this system only during sleep hours, but how can I close xDrip+ when not in use?
Surely silly questions, but I'm not so acquainted with such APPs, so cannot solve it by myself.
BTW, is there any kind of xDrip user’s manual?
Thanks a lot for your help.
Pippo

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Hi, Pippo, welcome to the forum!

To stop the low alert when it first rings, I suppose it might depend on how each phone is set up, but with mine, I can either just press the volume down button a bit, or pull the notification window down and stop it from the notification there.

But the snooze function will then kick in so it will ring again about 20 minutes or whatever its set to if you're still low after the snooze time had passed. Useful if you want to be sure you get another alert if still low, but a nuisance if you've treated and are just waiting a while to come back up.

There's two ways round that. Probably eaier to show with pics.

First one is to go into the main menu from the three horizontal lines at top left, then click Snooze Alerts, which will bring up the following screen, on that it'll show the alerts currently snoozed, and you can click Disable Low Alerts. That'll switch off the snoozed alert.



The other way is to go into the main menu, then Settings, then Alarms and Alerts, then Glucose Level Alerts List, then select the alert you want to edit by long-pressing it to bring up the following screen, then just edit the Default Snooze time, then scroll down to Save Alert. I've used this on high alert: normally takes longer to bring a high down so I set the snooze time to 2 hours to save it bothering me in 20 mins.



I've not been able to find a user manual, just spent ages sitting pressing buttons!

Good luck with it, I've been using it for about a month now, takes libre into a different league!

JoeT1 said:

Ordered the blucon so I'm very interred to give it a go. It works over Bluetooth right? Not just NFC?

Also downloaded xdrip, but I'm guessing I can't do much until I receive the blucon

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The blucon reads the sensor with nfc, but then uses bluetooth to send it to the phone. It's because nfc only has a very short range of a few centimetres, whereas bluetooth is several metres.

If you want to give xDrip+ a shot before blucon arrives, in Settings, there's an option NFC Scan Features which would let you scan the sensor with the phone, assuming your phone has nfc. However, it says it's experimental and there's no guarantee it won't kill the sensor. I've not tried it, but I suppose it would be possible to give it a whirl on the last day of a sensor so just to see what happens.

PS: now that xmas is coming up, maybe drop a few hints about how great smartwatchs are! Might as well go full bling!



Only had a glance through the instructions, but looks like you can make the watch collect readings so doesn't matter if phone is out of range.

novorapidboi26 said:

Is that xdrip on the watch....nice...

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Yeah, it was a bit of a late 50th birthday present to myself! A Fossil Q Explorist.

I was in two minds about getting it, thought it would maybe be gimmicky overkill, but it's been surprisingly useful, just being able to have a quick glance instead of dragging the phone out, have caught a couple of developing highs/lows I'd maybe have missed with just the phone.

Of course, there's the novelty value of it at the moment - you know what it's like, guys with new toys - so that'll probably wear off after a while.

Should probably take another photo - that sharp bounce up from 5 to 7.7 doesn't look great - was an underbolused Heineken!