MM sensor users: do you trust your sensor data enough

…to bolus for food or corrections?

Do you trust your sensors (be they Enlites or the newer ones) enough to not test with a meter more than 2X a day?

Do you trust your sensors enough you are lying in bed?

(I’ll have another thread for Dexcom users)

I’m on the Enlite / 630g.

NO. No I do not.

It isn’t uncommon at all for me to get an alarm from the sensors and my actual blood sugar be off by 100% or more from the sensor value. (Especially at night. It loves to wake me up because I’m low. It’ll say I’m 70 or 65 or somewhere in there. I’ll get up and test, only to find that I’m at 175 or 180.)

So no, I don’t. I’m thankful that I can sense when my BS is dropping. My aunt cannot. The MM sensors would be useless for her.


I’ll add that when I was on Enlites,most of them were random-number generators. In about a year, I had maybe 3 or 4 that gave decent results (during the day) for 6 days or more. Sadly for me, some of the best ones came loose from excessive sweating, long before the 6 day wear-period was done. When that happened, I was so bummed, because most of the sensors I wore were useless.

So to answer the question I posted in the OP, “no” I wouldn’t trust the Enlites for bolusing, or much else, for that matter.

When I first started out with the 670g and the Guardian 3 sensors the sensor would be all over the place compared to what my bg said. Currently like tonight it was 2 points away from what my bg was. Now I’m not saying I would trust it because it can still be a gap between my bg reading. In the beginning I had to shut off the low shut off/Alarm features as it would alarm at 3am saying I was at my low setting of 70 mg/DL but when I checked my bg I would actually be 140 mg/DL. In conclusion I use the sensor only as a quick guide as to how my bg is reacting to an after meal bolus or just a quick glimpse. I still depend on my bg reading and my sense’s for any intervention I would need to take…


That example of discrepancy at night is what I dealt with nearly every night for about a year, when on Enlites. How they ever passed FDA approval is beyond me.

Again the other night while calibrating my sensor twice my bg was only a couple mg/dL off from what my SG was. I think they have made some advancements with the guardian sensors but even so I wouldn’t trust the reading for anything other than to see where my bg was heading. A friend of mine who was on the 630 and upgraded early has told me that she had a few box’s of bad Guardian 3 sensors. I know the 690 is in testing/beta trials but there is a tight lid on about it.

I believe this clinical trial (link below) is regarding the 690G.
Estimated study start date: September 1, 2018
Estimated primary completion date: December 31, 2019
Estimated enrollment: 112 participants
Recruitment Status: Not yet recruiting
(I always wonder how accurate those dates are or if they just change whenever and they are really placeholders - more or less.)

The treatment being tested is listed as:
Device: Medtronic 670G hybrid closed loop system
Device: Medtronic advanced hybrid closed loop system
(where one would assume the 670G is the control)

The control group would be using the 670 while the test group would be using a:

… different Medtronic Pump very similar in nature the 670G but this has a slightly different algorithm called PID + Fuzzy Logic) to adjust insulin delivery based on the Enlite 3 CGM data in open loop or auto mode …

Just a little add on comment about the Guardian 3 sensors, I sometimes get the 7 day use out of one but mostly it is 4 to 6 days before issues force me to change out. One of my calls to Medtronics help line gave me the reason why and to share what they told me is that everyone’s chemistry is different and changes so what actually sends you BG out to your pump is the rate at which the metal strip coating of the sensor decays/erodes. So with some understanding I now have an idea why I have to calibrate so much more often in the beginning life span of my sensor and also why the lifespan can change as it depends on how much my chemistry changes during it life cycle

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Interesting info, @Trish1, thanks. There definitely seems to be a lot of variability in how long Guardian 3’s last for people. I routinely rolled them over and got ~12 days out of them. At that, the limitation was battery needing to be recharged; the sensors themselves were still fine. So it’s not a universal problem, but it’s certainly a common enough complaint, and the explanation you got makes some sense of why it’s a big deal for some people and not for others.

That doesn’t seem to be an issue for Dexcoms. Occasionally you might get a bum sensor right out of the box, but I don’t think I’ve ever seen the same kind of complaint, where certain people just can’t seem to get a full session out of 'em no matter what. There must be something fundamentally different in how the Dx sensors react to the biochemical environment that keeps them from doing this. Only limitation I run into with G5’s is how long the sticky tape hangs on.