If what you are asking about is as phoenixbound described then,yes, it is completely normal, even expected.
It would work the same way if you checked your ISIG immediately after your pump connects to a new sensor. In my experience the first one or three ISIGs will always be very high but will fall to zero relatively quickly. What I believe is happening is that the transmitter is attempting to find a “zero point” (for lack of a better term) for the sensor. I posted about this once back in May. The quote below is taken from that post.
<ISIG value> @ <time> every 5 minutes during 2 hour Medtronic sensor WARM-UP.
ISIG 123.12 @ 13:34; 43.94 @ 13:39; 00.04 @ 13:44; 55.66 @ 13:49
ISIG 00.00 @ 13:54; 00.00 @ 13:59; 02.14 @ 14:04; 25.02 @ 14:09
ISIG 30.36 @ 14:14; 32.08 @ 14:19; 35.32 @ 14:24; 38.46 @ 14:29
ISIG 40.38 @ 14:34; 42.18 @ 14:39; 43.26 @ 14:44; 45.40 @ 14:49
ISIG 47.06 @ 14:54; 47.04 @ 14:59; 48.04 @ 15:04; 46.76 @ 15:09
ISIG 45.78 @ 15:14; 46.74 @ 15:19; 47.92 @ 15:24;
I believe the extremely high ISIGs immediately after connecting the transmitter is an illustration of why Medtronic urges folks to connect the transmitter as soon as possible after inserting an Enlite. What they probably want to discourage is the habit some had with the older Sof-sensor (aka Harpoon) of inserting in the evening and then waiting until the next morning before connecting the transmitter.
Medtronic claims letting an inserted Enlite sit that long without connecting the transmitter could damage or even destroy it. Apparently when the sensor is not connected to the transmitter there is a buildup of hydrogen gas around the probe. The transmitter drains the charge from the sensor preventing the accumulation of the hydrogen gas. In fact, the current from draining this charge from the sensor is the ISIG. (The symbol I is commonly used to represent electrical current. Thus, ISIG is probably shorthand for “current SIGnal”.)
@acidrock23 I would be curious what ISIG value you get when your pump first connects after you have inserted a new sensor. If I recall correctly, you always wait at least 15 or 20 minutes between inserting and connecting while waiting for the transmitter to charge. When I used to do something like that my first ISIG was always ~400 or larger.
Yep. That’s the bottom line.