Re: [IP] Sensor Questions
-------------- Original message --------------
From: "ANGELA CLEVERSY" <email @ redacted>
> I have noticed on some of your postings you have mentioned getting 9 days
> out of a sensor before you change it. How do you know it is bad?
I usually leave mine in for 7 days - changing my sensor is my Sunday ritual.
However, when I first started using them, I had some go bad. The main thing I
noticed was that my sensor readings more or less 'flat-lined' when my BG was
Also, the ISIG value is very important. For some reason, Medtronic doesn't
document this, but the 'calibration factor' is critical. Their help line
explained it to me: The calibration factor is BG / ISIG. (Actual BG from a
reliable meter). That factor should be between 1.5 and 20. If it is not, you
will probably get a CAL ERROR. It seems my sensors are most accurate when my
calibration factor is 8-12. BTW, the ISIG value is shown on the 4th screen-
'sensor status' - when you look at your sensor readings.
Also, if the reagents in the sensor get used up quickly (due to prolonged high
BGs), the ISIG value will drop rather dramatically. I had one sensor that had a
ISIG of 3 or 4, so the sensor was just bad at that point and had to be replaced
(after about 5 days). Since I have gotten under a lot tighter control, that
hasn't happened in a while, and I can easily get 7 days out of a sensor. There
are a lot of people who can get 2-3 weeks out of them. Any time I have left one
in for more than a week, though, it makes a scar that I don't really like, so I
don't do that.
I'm still learning a lot about them. I've only used about 25 sensors so far in
5 months or so. There seems to be some kind of alchemy going on with them that
continually amazes me.
One final note: The transmitter has a built in 7 day death wish on its battery
life. If I put a new sensor in at 10:00 Sunday morning, I have to recharge the
transmitter before 10:00 the following Sunday, or it dies, and has to be
recharged for 20 minutes or so.
I hope this helps (actually, I hope I know what I'm talking about :-)) There
are a lot of other tricks you can find out if you poke around enough.
dx 1985 at age 32
MM 522 8/07
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