For three and a half days, the Dexcom was accurate and spot on. On the fourth night, I had hours of "???" during which time I went hypo and the Dexcom of course didn't alarm that I was hypo but it also didn't let me know that it wasn't checking me. On the Guardian, I would have gotten an alarm to let me know I wasn't getting readings.
In the AM, the readings started again, and I got readings all day, which I ate and bolused off of. In the evening, I checked my blood sugar: 104 vs Dexcom 178. I am not impressed. The Guardian never conked out on me in four days. Never ever.
I called Dexcom support this morning and they said they usually want people to wait for three hours of ??? before they replace a sensor, but that she could have them replace my sensor at that point. I said I'd wait and see.
The thing is, if most of the sensors were conking out at 4 days, then I'm not sure the money is worth it, so there'd be no point in them sending me another sensor, because I'd just be returning the Dexcom. Unless they're willing to keep replacing sensors that don't last? I dunno.
That I had a 104 in the evening suggests to me that it was pretty close during the day, because I ate about a gazillion uncovered carbs during the day on the advice of the Dexcom, which must've been right. But still...
I'm keeping this sensor in for now, and we'll see what happens.