ISIG Ranges--could use some help, please

I need to know what acceptable ISIG levels should be when starting a new sensor.

I have had a horrible night/day--36 hours. Now I am on my third new sensor of the day, and ISIGs are sitting around 10. Let's see--Cal Error last night (pump thought I was below 40, but tested at 103--stupid thing never believes me,) so turned sensor off at 1 AM. Low of 33 at 3:30, followed closely the dreaded Button Error. Now on a back-up pump and my third sensor of the day--first one had no ISIG reading, second one was an extreme bleeder and now the third one is reading what I think are low ISIGs. Oh and the third one pulled up a sensor error.

After last night's low experience, I am terrified to sleep without a sensor.

I am using my back up pump, which is a MM 522, which was last used a while ago--5 years, maybe. Mini Med tells me the technology works with the current stuff--I was on a 523 before the Button Error..

Discouraged is the least of my problems. I just want to get all the equipment working so I can feel safe enough to sleep. Will it work at an ISIG of 10? I know there is a good range, but I searched discussions, as well as my notes and could not find that.

I think you are asking the wrong question ... or at least focusing too much on ISIG without looking at other possible considerations. Also, you did not let us know which Medtronic (correct?) glucose sensor you are using: Harpoons or Enlites? Either one can be used with either the x23 & x22 Medtronic pumps.

If I had to make a guess it would be that you are still using the Harpoons (aka Sof-sensor) since you had a problem with one insertion being "an extreme bleeder". While that can probably happen with an Enlite, in my limited experience it is a lot more likely to happen when inserting ye old Harpoon.

On the other hand, you refer to Medtronic telling you that "the technology works with the current stuff". I assume "current stuff" is a reference to your 522 backup pump? Or does it mean something else?

For whatever it is worth, I'll give you my current operating theory working with the Medtronic CGM. First, it does work. It is not completely worthless as those of us who have been driven to hair pulling frustration can sometimes feel. However, in my very personal opinion Medtronic's CGM does have a number of design deficiencies.

I think the biggest potential problem after insertion is the sensor probe "moving around" in the insertion site. I think this is partly due to bad design. Medtronic has their sensor probe positioned at the end of an assembly which can act as a lever to dislodge the sensor probe. Contrast this design with the Dexcom sensor where the probe is underneath the assembly and further from the endpoints.

I think securing the sensor in place with a skin adhesive and/or overtape is often necessary to get it to perform correctly. I have been trying to work on this with my own sensors and I think it has been helping.

So where are you inserting? How are you securing the sensor after inserting? Which sensor are you using? It's hard to guess what to suggest without having a better idea just what it is you currently doing which does not appear to be working for you.

T1 LADA since ~1978, first pump 1997: Minimed 507
currently: Minimed Paradigm 723 (04/2013) + CGM (11/2014)

Using the "harpoons." I usually use AR's designation for it--10 penny nail. Still love that, AR.

Yes, I was referring to using the much newer sensor and transmitter with the 522, which is my back up. The date on the 522 when I reprogrammed it today was 2005.

I have been on a MM sensor for 6(?) years, but longer on the pump, as well as the proceeding Disetronic pump. Today's was only my second sensor bleeder ever. I have been happy with the MM sensor, insert it in my abdomen, and secure with Tagaderm.

I did get a request for a reading after two hours. Just did an additional BG reading and it was 17 points different from the sensor. So far, so good.

And ISIG is important, and was the correct question. I wanted to know if an ISIG of 10 would allow me to start the sensor safely. After my experience last night, I would be very fearful to sleep again with the sensor.

I had a bad day yesterday--and with 53 years experience with T1, I can recognize a bad day pretty fast. Day to day, I do fine, have an A1C of 5.4, but sometimes everything just slips. I mean one day where BG went from 91 to 210 in less than an hour (BG meter readings and not food related,) fighting highs carefully all day, Cal Error, Button Error, back up pump, Sensor Error, calls to Medtronic. I just wanted some basic info and after looking online, went for the helpful place, TU.

And ISIG is important, and was the correct question. I wanted to know if an ISIG of 10 would allow me to start the sensor safely.

I disagree. ISIG is meaningless without the context of a BG reading. You can't ask whether an ISIG makes sense without also considering the BG that ISIG is supposed to be connected with.

In my previous history with the Harpoons an ISIG of 10 could match to a BG anywhere from 70 to 100 mg/dl. An ISIG of 10 is low even for a Harpoon and if your BG is actually a lot higher than say 110 (as a guess), then I would wonder if the sensor is working properly. (Possibly a "kink" in the sensor probe?)

The Harpoons should work fine with your 522. (So should Enlites. Though the Enlites will report higher ISIGs for the same BG than a Harpoon, at least in my experience.)