I did indeed read the manuals.
The problem has been, very specifically, the Guardian 3 sensors that th 670g relies on for SG readings. These will often fail (go into “updating sensor” mode) after two or three days, which is typically followed by a message that the pump is falling back to programmed mode, then three hours later by the “replace sensor” message.
I have also had one sensor fall off seconds after insertion (never got to the transmitter) due to bad adhesive, and one where the needle bent on insertion, meaning that I had to sacrifice that particular sensor since the needle couldn’t retract. Add in the ones that tell me my BG is <50 and dropping (when multiple external meters tell me 100 and rising) and there are problems.
All of these problems are aggravated by the fact that if you should be away from home and need to replace a sensor, you can’t just carry a spare sensor. you also need to carry around the “Serter” and extra adhesives. This is in sharp contrast to the Dexcom sensors (I used G4) that come complete with a disposable insertion device. There’s much less to lose.
I understand that the 670g has to “learn,” but in order to do that, the sensors have to be durable and reliable–but they’re not.
In my experience (which may be onlymy experience) Guardian 3s have nowhere near the reliability of the Dexcom sensors. I also think that there are some physical design problems with the sensors: Seriously–you insert a small, flexible wire beneath the skin, but to attach the transmitter, you need to apply substantial force at 90 degrees to the insertion site, which is asking for trouble. And you place the sensor on a tiny adhesive pad, and attach a much more massive transmitter to it (thus the requirement for extra adhesive tapes). IMO, Dexcom’s approach (placing the sensor at the center of a large adhesive patch and bracing it with the transmitter mount, then attaching the transmitter with a downward motion) is a significantly better thought-out design.