Ok, that's weird. Maybe I should wait a bit? That's only 90 minutes of weird numbers. Yeah, let's give it some more time.
Now 3 hours of this? Jumping from 12 with double arrows up to 5 or 6 with arrows down? I did some fingerstick testing through this, and I was gradually rising. I went from about 7 to 10 over those three hours, but verrry slowly. My real BG values were definitely nothing like what the sensor was showing me!
I called Medtronic to ask if this sensor could be saved, whether by restarting it or recalibrating. The rep explained that results like this were most likely from the sensor being pulled partway out of the skin. When the sensor is pushed back, deeper into the skin, it becomes fully saturated with interstitial fluid and will give a higher BG reading. When the sensor gets pulled partway out of the skin it isn't reading as much interstitial fluid, so the sensor BG values will be low.
I waited it out and the problem continued, so I removed the sensor. The whole thing was bent, almost by 90 degrees!
This whole thing has been way too frustrating. I'm getting very, very sick of getting only 4-5 days of usage out of each sensor instead of the full 6 days.