Medtrum - the new low cost CGM solution now being sold

[tim2000s]

The lifespan of the sensor is pretty good so far. At the moment, the adhesive is holding my Medtrum in place better than the G5 on the other arm, which is cover in Kinesiology tape.

In terms of restarting, I flipped the switch in the app to give 14 days life. That doesn't seem to have caused any issues. What I did find was that on day 8, the transmitter and phone stopped communicating properly, with the battery showing in the app somewhere around 50%. I popped the transmitter off and charged it, which seems to have resolved the issue, however, it causes the transmitter to believe it has a new sensor.

One thing that's become very clear is that in the first week, the readings were on average 7% higher than blood values. So far, five days into the second week, they are reading roughly 5% lower than blood on average, so there is some inconsistency across the time period. For comparison, in the first week, the G5 was, on average, 0.1% lower than bloods. In the second week so far it has been 10.8% higher than bloods. This all has interesting implications for those using these things for closed loop applications.

In terms of placement, they've licensed it for abdominal use, so are well within their rights to complain about arm use...

 

[slip]

they've licensed it for abdominal use

Perhaps this needs mentioning in the user guide - it reads more of a suggestion of placement rather than anything else.

I've already set my app to 14 days ready for when I get my replacement - which will be located on the abdomen.

2 days in wearing the blank sensor and no reaction issues, itchiness or anything........

As ever Tim you're a star.

 

[Brunneria]

Thanks Tim.
That answers my question about variation of accuracy over time - although obviously your n=1 it does kind of suggest that the same issues could be in play as I get with the Libre.

 

[redditchdiabetic]

Medtrum have updated there software on my Andoid phone to Improve some bugs to improve system stability and changed the Low glicose alarm, I have tested around 6 times today before food and after the results compared to my Blood have been very accurate indeed.

 

[slip]

I’m up and running, very easy insertion, longest 2 hrs of my life waiting for the warmup period to end, obviously prompted for a calibration meter reading straight after. The 2hrs is included in the 7day sensor life.

 

[slip]

Not a bad day! Although sensor is reading about 2mmol low but it is early days still.

 

[Scott-C]

View attachment 26631

Not a bad day! Although sensor is reading about 2mmol low but it is early days still.

Is it 2 out even after calibrating it?

I've had a few situations with libre/blucon/xdrip where it just doesn't seem to "hold" a calibration and will be wandering a few hours later, and other times when it stays on song for the whole day.

 

[slip]

Is it 2 out even after calibrating it?

I've had a few situations with libre/blucon/xdrip where it just doesn't seem to "hold" a calibration and will be wandering a few hours later, and other times when it stays on song for the whole day.

So wasn’t helped at first calibration/ start I was 3.3, and it took ages for it to register I was back in range very soon after, later did another calibration and bg was 6.6, sensor was saying under 4, with in a few mins sensor was reporting low 4s - so not holding calibration, this mornings calibration was way out bg 5.6 sensor 10.6, its been reporting mostly 2mmol lower today, but just checked now and within .8 so getting closer without further calibration, due at 9:30pm.

No reactions to the failed sensor which I’m still wearing as well.

I tried not to keep calibrating whilst healing/settling in, just wondering when best to calibrate, 9:30 is 2-2.5hrs after meals......may be later it better?

 

[Raralalala]

I've been reading this religiously as my daughter currently uses the G5 but it's killing me financially - think I'm about to place an order for this, can we definitely get up to 14 days use of a sensor even if it is only guaranteed for 7?

 

[tim2000s]

@Raralalala - I'm not aware of anyone who's been in the early use stages getting 14 days. I managed 11, and it was noticeable that there was a change in performance after 7 days. I'm in the process of writing up some data, but given both Dexcom and Medtrum state a MARD of 9%, it's worth mentioning that in the 11 days of use, Mean Absolute Relative Variation from Blood (an approximation for MARD using a standard fingerprick test in place of a Yellow Springs Instruments venous analyzer) was interesting:

• A6 was 14% while the Dexcom G5 was 10% over the life of the Medtrum sensor
• A6 was 13% while the Dexcom G5 was 9% during the first week

The other thing worth looking at is the Mean Relative Difference from Blood:

• A6 was 5.5% versus Dexcom G5 at 0.1% over the 11 days of the Medtrum sensor
• During the first week, A6 was +7.1% while G5 was -2.1%, meaning the A6 read higher values than the blood reading in most cases, whereas the G5 read lower. Directional can be skewed by one or two big misreadings, it's also worth adding
• During the second week, the A6 was -3.4% and the G5 was +11.1%, suggesting that once you're past the 7 day point with the G5 that its accuracy drops off.

In addition, the readings above or below current blood test stack up as well:

• Week 1, 62.5% of A6 readings were greater than blood tests, while 32.8% of G5 ones were
• In the second week, 50% of A6 readings were greater than blood tests while 58.3% of G5 readings were.

Based on that first sensor I wouldn't want to dose from the A6 over the first seven days of use, but the performance doesn't appear dramatically different from Enlites used with the older medtronic pumps.

 

[slip]

These are my scores on the doors FYI

 

[Scott-C]

just wondering when best to calibrate

The stuff I've read (Sugar Surfing and Beyond Fingersticks) suggests calibrating when relatively stable and generally in range.

I try to calibrate in the morning as there's a fair chance then that glucose in blood and in IF will be broadly similar due to not eating and resting, so it improves the chances of accurately matching what the sensor is reading to blood.

I made the mistake of overcalibrating in the early days trying to chase down rapidly changing levels but soon realised that just makes it worse - if I've just eaten and glucose has gotten into the blood but not yet into IF, there's no point in telling it 7.7 from a bg test when the IF the sensor is reading might still only be 5. It's then going to think that when it's getting a raw reading which is actually about 5, it means 7.7, which just throws it way out.

So, I'll tend to aim for a calibration in the morning as bg and IF are likely to be about the same. Maybe before evening meal, and before bed.

 

[redditchdiabetic]

I also try and callibrate when i have no insulin on Board and when the Medtrum is stable, It would be interesting based on Tim's excellent analysis if the latest update by Medtrum has improved there readings. My sensor lasted for around 8 Days and then got some strange results so i took it off, The answer to people's question is yes it can go further than the 7 days but the results can be up and down.

 

[Scott-C]

It's a new product, so will doubtless go through a few initial teething problems, and upgrades, but it's a bit of a worry that the, "will it last for 7 or 14 days or somewhere in between" issue is so hit or miss.

It makes a major difference to self-funders trying to price these things.

50 or 35 quid, depending on where you buy it, or free depending on how liberal your ccg is, for a libre which will pretty much definitely last for 14 days.

50 quid for a dexcom, which, well, most people can drag 14 or 21 days out of it if used off-plan, although some only get 9 and some get 28.

35 quid for a medtrum, which will do 7 days, and maybe it might do 9, 10, 11, 14 but who knows.

It's that lack of certainty about how the second week might pan out which is offputting.

I'm reasonably certain with libre that I'm going to get 14, so I can plan ahead for when I'm going to attach to get a 24 hr resting period before activation, but with medtrum, it seems more hit and miss as I simply wouldn't know when in the second week it's going to tank, or whether I need to budget for 2, 3 or 4 sensors that month.

 

[redditchdiabetic]

This is now my third sensor and is the best so far maybe a combination of Medtrum's latest update and I only callibrate first thing in the Morning before Bolus and Food and also Evening meal, I think the key is callibration my last three days have been almost the same as my Blood sugars.

 

[slip]

I’m finding accuracy isn’t bad either, can’t say I’m calibrating particularly well put it that way.

For those that react to the Libre like me, been wearing the ‘blank’ sensor for a whole week now and no reaction and still stuck firmly.

Just hope my working sensor continues well after 7 days.....!

 

[tim2000s]

LAtest update: http://www.diabettech.com/cgm/medtrum-a6-cgm-a-week-or-two-in-the-life/

The second sensor isn't showing the same level of skew that the first did. It's more mediated. It's not a great deal more accurate though, with the first four days showing a Mean Absolute Relative Variation from Blood of 19.4% on the A6 vs 10.2% on the G5. What I have noticed is that there is a real tail in performance as you approach the next calibration point. I've seen some properly wide values at that point in time.

For what it's worth, the graphs are:

 

[redditchdiabetic]

Great piece of Reporting by Tim sorry mate you lost me with all the High Tech analysis. I am happy with the Medtrum all my results over the last few days have been spot on very similar to when I had the Dexcom G5, Just noticed Tim that they have just released a further update, Would be interesting if you run the Same analysis now with a new sensor on after 2 Medtrum updates would the figures change?

 

[tim2000s]

@redditchdiabetic I'm running the most current version of the software on the iPhone. Can't say I've seen a bunch of updates. Unless they're updating the transmitter every time they update the phone software (which I don't believe), then that shouldn't make a lot of difference.

The second sensor seems to have settled into a much more effective tracking of blood/Dexcom than the first did though. That does beg the question about sensor consistency.

 

[redditchdiabetic]

Tim2000s I have had 2 updates so far on my Android device one on the 18th May and the other 24th May and the latest software you should be using is 1.3.5 (56)