It ended up after purchase of 2nd CGMS that boys in puberty have such rapidly moving BG levels that the system couldn't keep up. We have put it aside for a while to give him time to level off.
Cindy I had the opportunity to get some good info this summer from a medtronic technical expert. I had a lot of problems with the CGM's before I knew this info as well. Here are the most important pieces of info she gave me:
1. Calibrate only 3 times a day. Once before breakfast upon waking, once before dinner, and once before going to sleep. These times are chosen because they are spread out and the blood sugar should be stable during this period. If the blood sugar is rapidly changing at these times (indicated by 1 or 2 trend arrows) do not calibrate. Wait for it to stabilize, then calibrate.
2. Calibrate 3 times within the first 6 hours of having the sensor inserted to get it set up. So first the pump will ask for a BG about 2 hours after starting, then enter one 2 hours after that, and then 2 hours after that for a total of 3 calibrations in the first 6 hrs. Again, calibrations need to be when the blood sugar is stable so I usually do this in the morning and have a protein breakfast (so my BS is stable) or skip lunch and do it from afternoon-dinner time.
3. Turn off the communication between your meter and pump. If the communication is on, all meter BG's will be used for caibration, which is bad. More than 3 caibrations a day (besides on the first day) will screw with the algorithm. And of course, if your son is exercising or something that makes their blood drop rapidly the sensor wont be able to follow it and they will have to test.
4. Don't use sticky preparation material where the sensor goes in. I used sticky Tac but it throws the sensor off, so only use alcohol rub (I insert the first half of the sensor then use sticky tac under the rest of it).
if you give me your email I can send you a whole power-point on how to use the sensors properly that she gave me. Hope this is useful,
ive gotten bad sensor message before, but it was because i had a faulty sensor. and teenage girls seem to do just fine with sensors.