I’ve been on the Minimed 630 for roughly a year and a half or so. I’m on the wait list to get a 670, thanks to their free upgrade program, now that my insurance finally accepted the upgrade.
But the CGM is driving me nuts on the 630, so I’m kind of afraid to plunge into closed-loop territory when I get the new pump. When my 630’s CGM is working correctly, it’s an awesome thing that helps me.
But sometimes, it’s just dead wrong. For example, last night around 1am, it woke me up, alarming that I was at 70. This was the second night in a row of this, and I didn’t trust the sensor. Sure enough, I checked and my blood sugar was actually 170. I didn’t calibrate (any time I calibrate when the sensor is that far off of reality, the pump rejects the calibration).
So over the next four hours, my pump continued to give false alarms until it finally decided to shut off my pump at 5 am. I got up, re-tested my sugar, took a correction bolus, shut off the sensor and turned my basal delivery back on, and went back to sleep. I turned it back on after my shower, calibrated again (my blood sugar had actually gone up). The calibration was successful. But then about 11:30 am, it again alerted on low. I tested and was high, and it rejected the calibration.
I killed the last sensor 2 or 3 days early in the same cycle of false lows ending in 2 failed calibrations in a row and the pump ending the sensor early. I’ve learned that calling Medtronic after the half-way point usually means a waste of time. But about every 6 weeks, I get to call their support line (they have great support people, really), and explain that yet again I’ve fried a sensor. They mail me out a new one and I go on about my business.
But I’m scared to turn my bolus delivery over to a sensor system that’s so frequently out of calibration with reality. I’ve asked Medtronic folks a couple of times, and their response is “Oh, sure, the new sensor is better!” but I feel like the sales folks aren’t really listening. And the support folks are trained to deal with specific inquiries that aren’t that general. My doctors don’t really know enough to answer me either.
The two-hour window between inserting the new sensor and the first calibration means I have to be careful how I plan for changes, so these unplanned failures throw things off every time.
I guess I’m just frustrated. And nervous. I’m careful to calibrate when the pump isn’t showing arrows indicating BS changes, or when I have active insulin from bolus deliveries… But I keep having problems with failed calibrations and/or wildly inaccurate sensor readings. I don’t really know why.
Sometimes, I know after the fact, because there will be blood at the sensor site when I change it out. But most of the time, there’s no way to know.