ANY ONE OUT THERE HAVING TROUBLE WITH THEIR CGMS READING CAL ERROR AND BEEPING LOW 'S, AND WHEN YOU DO A FINGER STICK YOU GET A NORMAL BG
Which CMS system are you using? Did you check your ISIG (interstititual fluid signal) values when you got the CAL errors?
I only get CAL ERRORs after about the eighth day of wearing a sensor (Medtronic CGMS). It does not seem to be associated with low readings. Other times the finger stick does not match the CGMS reading, like right now it says I am 270 but my finger stick reads 142. I’ve swung up and down today since I spent yesterday traveling across all four time zones here so I’m trying to get the sensor back on track.
I have the Metronic CGMS also, and typically don’t use a sensor more than 6-7 days (when the thing times out) since my insurance pays for 3 day use.
That said - if I had a discrepancy like what you experienced, I’d restart the sensor again (to clear out previous callibration values), and callibrate again when your blood sugars are relatively flat. That way you’re starting fresh.
Also - I find the closest correlation between BG and SG when ISIG values are between 11-17 (or higher). ISIG values will drop over time the longer you use the sensor. So if things don’t correct it might be time for a sensor change.
hi jason,thanks for the info,please tell me how you get away with wearing your sensor for 8days?does it leave scaring to stay in place for that long?i only leave my sensor in for three to four days,i am going to have to start changing it out in three days because my sites are leaving scars.ANYBODY OUT THERE SENSORS SITES ARE LEAVING SCARS/////JASON SEND ME A REPLY ASAP//THANKS///MAY I ADD YOU AS A FRIEND
Actually, I don’t have a problem leaving them in a long time with regards to scarring. They leave less of a mark than my pump infusion sets which stay in for about half as long. I guess everyone is different, but you should talk to your doctor about any options that may be available to alleviate that problem for you.
Feel free to add me.
I haven’t had any scarring issues using sensors for 6-7 days. Can’t really speak from much experience using sensors longer than that although I did try extending a couple them to 8-10 days which I stopped doing cause SG results were not very good for me beyond 6-7 days (YMMV).
Getting back to the original question from Odessa - usually CAL ERRORS usually occur when Sensor ISIG values (hit esc key 4 times) are lower than 5 when you callibrate. You should never callibrate a sensor when ISIG’s are that low - either wait to callibrate until ISIG rises above 5, or change the sensor.
I’ve found that some sensor insertion locations (side of thigh for me) have consistently higher instititual fluid (and ISIG) levels than other areas (like sides of abdomen) do. Regardless of the sensor location ISIG values will drop the longer you use a sensor, and the Callibration Factor (BG divided by ISIG) will increase. This is not necessarily a bad thing (BG to SG correlation wise) unless ISIG falls below 5.
I can only use the snesor for 3 days–maybe stretch to 4
I do this–I take an alternate site test (runs approx same lag as is fluid) and a finger stick…if they are close I calibrate, if they are not I do not. This way my CGMS readings are almost always within a couple of points of a fingerstick unless I am trending up/down very fast.
I also get the cal errors when I have had the sensor in more than 6 days. I also get the cal errors when I calibrate when there was a significant difference between what the sensor shows and what my meter shows. Now, when I see a huge difference - like Jason’s 140/270 – I will test again in about 30 minutes and if the meter has me pretty stable, I will calibrate at that point. I will then get the cal error and have to retest and recalibrate, but this gets the meter and pump back in the same range again.
I also get the low alarms at times when I know I am ok. The CGMS always lags reality and sometimes overshoots. It is one of the joys of the technology.
All good points Jonathan. Another thing to keep in mind is that the pump remembers the last 4 BG callibration values (METER BG NOW) you input. So if things really get off-course between BG and SG you can always just turn the sensor off via the pump and restart it, just like you’d do after inserting a new sensor. Except the difference is you only have to wait a few minutes for the pump to prompt you to callibrate with a BG, versus having to wait the full 2 hours after inserting a new sensor and connecting it to the minilink transmitter.
Things are not perfect with CGM technology at this point, but I can say as a long-term user of CGM (2 yrs +) and long time pump user (23 years) this is the best thing to come around since insulin pumps and blood sugar meters became available. Much better than being in the dark on glucose direction between BG tests!!! Kinda like cellphones and HDTVs - how’d we ever live without them before. 
Another thing you can do Jonathan, especially if you’re not getting good ISIG values (or they’re varying too much, like is sometimes the case in the 1st 24 hours after insertion), is turn off the sensor from the pump for a few hours, then turn it on and start sensor again. The pump will prompt you for BG callibration (METER BG NOW) in only a few minues after you re-start it in this fashion.