Minimed sensor never worked, now trying Dexcom!

Hi all -
I have tried two of the Minimed CGMS systems because I have a Revel pump, but the calibration thing never worked despite working with a Minimed tech repeatedly. It was "cal error" hell. My CDE said I wasn't alone, that others had the same issue and that it was just our body chemistry. So now I'm trying the Dexcom, sounds like a much better-working system so I'm hopeful.

I just want to check because I'm not seeing anything in the literature about specific conditions when a sensor can be inserted. One thing I hated about the Minimed CGMS was the limited window of time you could start a sensor (not within two hours or a meal or exercise, if there was a full moon or if you're wearing purple, etc.). So I can insert a sensor anytime? Are there better times/conditions during the day that have worked better for anyone?

I live in a rural area with limited access to training, so I'm hoping you can help with this question.


try dexcom...

Hi Angie,
I had exactly the same issues with medtronic's CGMs and I am MUCH happier with the Dex system. It is way easier to calibrate, way easier to set up, and is much more accurate. To answer your question about when to start a new sensor, I have found it works best for me when my blood sugar is stable. I usually insert it an hour or so after I eat and bolus - so that by the two hour mark for calibration, my numbers are usually pretty stable. I would play around with this and find out what works best for you.
Hope this helps,

I'll insert a Dexcom sensor anytime AS LONG as it's at least 3 hours before I want to go to sleep. I've found that if I do the initial calibration just before bedtime it's often way off when I wake up and I spend an entire day getting to it read properly again. As long as there's time for it to really figure my body out before bed I seem to be much better off. Usually I just put a new sensor on when the old one finally falls off or gives me a sensor failure.

Hi Angi,
I used MM CGMs, and had some success, but also many frustrations. So I switched to Dexcom last year, and am very happy.

The first day of readings on the Dexcom can also be a bit crazy, but usually pretty accurate after that. So for the first day, I do try to enter calibrations on Dex when BG is somewhat stable, when possible. I usually insert the sensor early or mid-day, on the weekends. I agree, best not to do so just before bedtime. No need to 'wet' the sensor overnight as with MM.

I had bad readings on my 2nd Dexcom sensor, and learned that it was because I didn't have the transmitter 'snapped' in on both sides. There is a 'twist off' tab that is used to lock in the transmitter onto the sensor. You are supposed to hear 2 clicks. But now I double check it, and if needed use my fingers to get the last corner snapped in, and no more problems.

The other difference I noticed is that when there is a big difference between Dexcom and BG reading, Dexcom will usually quickly align up with the calibration, compared to MM.

Hi Angi,
One more difference between the MM & Dex: You should not put any IV patch over the sensor. Even if it is transparent. What I do and many others here do is cut out a template so (for instance) if you use an IV3000 pad, the template will cut out around the sensor. I have also not used anything and the sensor stays on easily for a week or longer. Dex also does not recommend using any IV prep solution under the sensor.

I haven't had ANY issues with sensor reading being off for the first day, or whatever. Also, I can put one on anytime, given that it takes three hours to startup, so putting one on at 10pm, say, is probably not a good idea. :)


I've found you really can start it at any time. Having said that, I generally insert it before I go to bed, then start the sensor in the morning so the enzyme that catalyzes the chemical reaction that makes the thing work has had some time to interact with the interstisial fluid.

Angi - I think you will be very happy with the Dex.

I used both as well and I was not happy at all with the MM sensor. I took a CGM vacation for a year after being on the MM one for 2 months - LOL!!!

Anyway, I insert at anytime and wear each sensor for 15-25 days.

At this point, I would feel completely blind without my Dex.

Good luck!!!