Posted by on Monday 31 August 2015

64 Days with the Medtronic 640G: Ep 8 Fine-Tuning SmartGuard

For all the times when SmartGuard has worked brilliantly for me (and there are - too many to count), there have also been a number of situations in which it seemed to make a bit of a mess of things. Overshooting and leaving my higher than I'd like... kicking in when a hefty carb load was just about to arrive and stopping basal for that 30 minute minimum (during which time I would be having a high glucose alert)... or cancelling various parts of dual and square wave boluses which I then may not spot until slightly too late.

I'm sure each user would have their own list - but these are my own #SmartGuardFails and some of the techniques I have tried to fine-tune the alerts and levels to work around them. It's interesting how irritating these odd occasions can be, and I suspect it is only because, well for me anyway, SmartGuard has worked so *brilliantly* for so much of the time that they really stand out.

If you have any MM640G SmartGuard tips and tricks of your own (or any other comments or questions), please leave a comment below.


  1. My dawn phenomenon happens in exactly the same way. I'm MDI & compensate by prebolusing & a higher breakfast ratio but it can be very frustrating at times.

  2. This is what worries me about any pump that calculates whether it should or shouldn't give insulin.
    If it gets that calculations wrong, or fails to stop giving insulin when I'm expecting that it should, it's my life on the line. In the hands of a cold machine. At least with pens or an ordinary pump, I've got no one to blame but myself if things go wrong.

  3. Hi Toothpik

    I think it's pretty natural for people to feel a little nervous about the automation side of things. I know plenty of people who are dead-set against pumps because they cannot summon the trust required to allow a mechanical device to take over dripping in basal and delivering boluses.

    Having said that it didn't take me long to see that the MM640G was doing what it should, and that in reality it was *far* better at spotting when I needed to set a 0% TBR than I was - simply because it was watching ALL the time.

    On the rare occasions that things didn't work out perfectly, they were only out by a bit (say 9.0mmol/L rather than 6.5mmol/L) which is significantly better performance than when I was using an infusion set that didn't suit me and set failures had me zooming into the 20s.

    On balance I'd say it was very easy to trust the MM640G to work well. In fact I'd go further and say I was longing for the next generation Medtronic pump which, if rumours are true, will also have the ability to *add* extra insulin where my calculations/guesswork have gone astray.