Calibration?


#1

My sensor and meter matched perfectly today until I calibrated about an hour before dinner, ate my dinner and then the sensor did not catch my high readings after dinner and looked like it stayed steady until I tested just now and I am sky high and it does not match my sensor, and therefore no beeping to warn me of the highs as I slept after dinner as we ate late.

I am very frustrated now as it seems every time I calibrate the thing is useless. :frowning:

Do I have to calibrate after the first day? I am very sad.


#2

Karen ,

How long had it been since you calibrated the last time ? If you calibrate then eat a high carb meal right then your bs may be moving to fast to catch up . The thing about this is it is not full proof all day long when your bsgs are moving fast it cant keep up . I only calibrate 3 times a day .When I fist wake up about 1/2 hr before i eat supper and at bed time. If my numbers are on the move at those times I just skip it if I lose time on the sensor I lose it bcs calibratng at those times are useless .


#3

My tech rep. told me a good analogy for the use of CGMS. Your glucose meter (finger pricking one) is like the first car on a rollercoaster and your CGMS is like the 5th car back. It takes a while to catch up to your actual sugars so only use it as a rough guide and to track trends. It’s not fool proof yet. YET. =) Good luck!


#4

If you have the Minimed RTS then your pump will remind you to calibrate every 12 hours. If you dont calibrate, it will shut down, unfortunately. The reason this was put in was because the FDA is not an organization that you can just dump a CGM that replaces BGs and expect approval. You need baby steps in approval to get to the final goal of a complete replacement of an existing technology. So, Minimed introduced this whole calibration thing to appease that.

It is completely necessary to enter a value into calibration, but it doesnt have to be the one from your meter (sneaky huh?). If you hit that stride where your sensor will match your meter BGs, try and calibrate from the sensor reading rather than the meter. Your sensor will take the last 4 calibrations and factor them into transforming your “isig” into an actual BG, so when you add a calibration - it will calculate a new formula. Technically your CGM should match your BG to about 10 pts. Remember, it is reading interstital fluid and not the parts of your blood so it may be a little different.

Your best bet if you have WACKY readings from the CGM is to call Minimed’s 24 hour help line (if you have the RTS). They will take you through step by step in how to make sure your sensor is calibrated correctly. Truly a great service that has helped me numerous times.


#5

Thanks everyone, I just like when it matches my meter so closely and I do realize there is a delay and it is also interstital fluid. It just seems the calibration stuff messes it up. Never considered the FDA involvement.

Well today I waited until I was close to steady to calibrate, but when does that truly ever happen on the weekends and my little sister wanted to go shopping and the sensor stated bad calibration, when I needed the sensor the most while shopping, I was doing okay then driving home did not want to tell my sister I felt low, and she said I drove like a taxi cab driver, did not want to share with her the real reason and I shoved fruit snacks down my throat, got to her home hugged my two nieces and tested and bgs was 64. Man I was mad I did not have the sensor up and running. Seeing too much down time with this thing.

Thanks again for your help, oooo and what does ISIG stand for, don’t laugh if I should know. :slight_smile:


#6

Grrrr, woke up with bgs of 94 and sensor said 94 (HAD TO CALIBRATE!!!), two hours later after two cups of coffee, got a 78 low bgs reading on sensor and tested on meter and it read 172, grrrrr (morning spikes the last two weeks because of PMS).

This calibration stuff is messing with the sensor and messing with me!!!


#7

You could just use the Sensor reading as your calibration, try it out and see what the relationship is.


#8

I did that this a.m. when the sensor matched the meter, and got the calibration error.

I shut the thing down today and ripped it out this p.m.

Did not even try to save the sensor this time, but I am not giving up, gonna try a new spot tomorrow. When I pulled this sensor out, it was curved, not that should matter, I don’t think, it is not like an insulin site, grrrr.