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    « I Don't Do That! | Main | Continuous Monitoring: In a Sentence »

    Is the Grass Not So Green?

    Yesterday I swapped the Guardian RT for a Medtronic 722 pump. This is a temporary change as I currently only have the 722 on a finite trial arranged between my hospital and Medtronic. Even so, I've been looking forward to this. Since discovering at first hand the value of the Guardian RT and continuous monitoring I've become a total addict. And I was looking forward to a bunch of features that the 722 offers over the Guardian RT.

    Like 3 hour and 24 hour trend graphs right there on the status screens.

    Like the ability to restart an old sensor after the 72 hour cut off with only a 15 minute skip in data, rather than a full two hour initialisation.

    Like only having one unit to carry around, which apart from obviously being easier will also surely simplify matters on flights I am scheduled to take.

    But had I not already been a convert to continuous monitoring, had the 722 today been my first introduction, I think I might have thrown it out of the window and given up. And even as it was, I certainly began to wonder if things weren't better back with the Guardian. If the grass wasn't greener over here with the new pump.

    After starting up the new sensor on the pump, I patiently waited for the two hour initialisation to end, and the pump to ask me for a calibration fingerstick result.

    'Beep beep beep CAL ERROR'

    Ok... let's try again. 15 minutes pass...

    'Beep beep beep CAL ERROR'

    And then: 'BAD SENSOR'

    Gaaaah... Admittedly there was a likely reason for this: Unfortunately the timing of picking up and starting on the new pump, plus the timing of an important meeting I had on in the afternoon that meant I couldn't delay or skip lunch, the first calibration request fell just an hour after I finished eating. Cal Errors are the pump's way of telling you that it is confused because the data it is receiving from the sensor doesn't tie up with the data you've given it. Bad sensors can cause Cal Errors, but far more likely is that the blood glucose level is changing rapidly and so does not correlate well with the interstitial fluid glucose measured by the sensor.

    No matter. Without disconnecting the transmitter, I selected 'New Sensor' to restart, and just 15 minutes later (i.e without the full two hour initialisation) it asked me for another fingerstick.

    'Beep beep beep CAL ERROR'

    Ok, I was annoyed now, because this fingerstick was within 0.5mmol of the previous two. So over the previous half an hour or so my blood glucose hadn't been changing that rapidly. I angrily punched in the value again.

    Finally, a few minutes later I started getting readings and seeing the trend graph appear.


    The values on that graph? Not so great.

    Stress of my meeting notwithstanding, my blood sugars yesterday afternoon were horrible! I consistently hovered around the 12-13 (215-235) range. The pump painted an even bleaker picture though, shooting up to the graph limit of 17mmol (306) and staying there. So much for seeing trends. All I was seeing was a thick black bar dragging across the top of the screen.

    When my meeting was over I took what I guess with hindsight was a bit of a rage bolus, and fell from 12.5 (225) to 4 (72) in under an hour. Whether it was the rapid change or not, something was irking the 722...

    'Beep beep beep BAD SENSOR'

    "Ok... chill, I can deal with this" I said to myself. Restarting as I perused the menu at the restaurant we'd settled on for dinner.

    Right around the time my first margherita arrived 'Beep beep beep BAD SENSOR'. And to make matters worse I kept hearing little alarm beeps but with no accompanying alarm message.

    I guess having already used the Guardian RT was something of a benefit. If I hadn't experienced a couple of bad sensor alarms with that, and realised that the sensor is usually anything but bad, I would almost certainly have pulled the sensor out at this stage, if not long before.

    And probably followed that up by throwing the whole assembly against the nearest wall, or through the nearest window.

    As it was, I switched the sensor feature off, but left the sensor in place, enjoyed my dinner and a hot chocolate fudge brownie sundae for dessert.

    It was only when I got home and examined the sensor carefully that I realised that somehow the transmitter has come partially disconnected from the sensor. The "alarm beeps" I'd kept hearing were actually coming from the transmitter itself as the end engaged and disengaged slightly with pressure. I've never had this experience before, and the connection was tightly covered with IV300 so I still don't understand how it happened. The transmitter beeps are a new feature not present on the RT transmitter, so I wonder if this has been a problem for others and those beeps have been added as a warning system.

    Later, after reconnecting and initialising, and allowing enough time for that sundae to quit messing up my readings, I was good to go. Calibrated first time and normal service resumed. Since then I've had great accuracy and I'm very much enjoying not having two units to carry around.

    Oh yeah... and checking out those graphs. This is what I like to see...


    Perhaps I'll reserve judgement on the colour of the grass for a little while longer...

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    Very interesting post Caro!!

    Who ever would have thought that the connection had been disrupted!? Very good investigation! May I call you "Detective Caro"? hehe!!

    Awesome looking graph in the picture...that's what we like to see!

    Yeah... don't be fooled. The graphs don't always look like that! The small size of the graph also makes things look much 'flatter' than they really are.

    Isn't being a detective just another of those skills that diabetes gives us? Searching for the cause of that low. Or high. Or...?

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