CGM: My experience so far

When I started on CGM, things were going fairly well.  I was getting mostly accurate readings, and in general I had few complaints. My sensors felt ok, weren't overly irritating, and all of the alarms it gave me were for good reasons. It woke me up a few times for overnight lows, and overall I was starting to feel pretty cautiously optimistic about integrating cgm into life.


Lately though, I've been having some issues with my cgms. On Tuesday night I started getting "LOST SENSOR" alarms. After trying to reconnect to a sensor (one that was only 5 days old), and failing, I called Medtronic to ask what could cause an error like that. The rep told me it was most likely a transmitter battery issue, which to be honest was frustrating to hear. I charged the transmitter before starting my last sensor, so having it die after only 5 days was more than a little bit annoying. I removed the sensor and fully charged the transmitter after being told that Medtronic would replace the sensor that I had to pull out early.


My sensor stock was at 2, so luckily I still had enough to start a new one early. After the transmitter was charged, I tried out a new sensor...and then:






I've only been on cgm for about 3 weeks, and in that time I had not experienced any bleeding when I inserted a sensor. None. At all.


This time, though? SO much blood.  I followed the cgm instructions and put pressure on the sensor, and it stopped bleeding pretty quickly. I still had the issue of dealing with the blood-soaked tape that goes under the transmitter. The blood pretty much wrecked the stickiness of the tape, so I had to clip off some of it as I couldn't get it to stick to the skin. I called Medtronic again at this point - I know it might have been an overreaction, but as I'd never had any bleeding at all, I was wondering whether all of that blood would affect the sensor performance. The rep told me she couldn't say, and that it couldn't hurt to try it out, but not to expect much from it (I'm paraphrasing. She was much more professional than that). She also told me she'd replace the sensor. That's...um? Thanks? Not really why I called, but still nice I suppose.


She was right about the sensor, sort of. It had about 4 days of solid use (reliable numbers, etc) before it started to fail, but when it failed it failed hard. I went to bed with good sugars, and it spent an entire night waking me up with Low Suspend alarms every 90 minutes or so. I eventually turned off the low alarms and tried to get it to shut up, but the Low Suspend alarms just kept coming. By the time I woke up I was 18.6  -- buuut my cgm was showing a nice straight line.


It was only off by 12...

It was only off by 12 mmol/l... ( ~216mg/dl)


*sigh*... not exactly the number I wanted to wake up to on my birthday!


I switched everything yesterday, and this time made sure to separate my cgm and infusion set. I think part of my dissatisfaction with the sites and sensor might have been that the two were very close last time around, and both felt constantly irritated. When I'm always annoyed by a site, I'm just a teensy bit more prone to overreact to things.


Since changing both on Saturday I've been happier...ish. My cgm still trends lower while I'm sleeping, and last night (on a freesh cgm) I still got a few false low alarms. I finally googled it today, and found that apparently Medtronic cgms are sensitive to pressure. A few sites I read (mostly diabetes forums and comments from users) said that if you're sleeping on it, the increased pressure on a sensor can cause false readings.




I prefer to put my cgms in my back. They don't bug me there, and I find the sites to be much more comfortable (aka easier to ignore). I just started a new sensor yesterday, so I've got quite a bit of life left in it - but after this one I'm thinking of trying some new areas. I read a few good things about sensors in the top of the thigh, and I've never had issues with infusions sets there. Some users also recommended the arms, so that's another for the "maybe" list.



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