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Getting cal errors on day 7

Discussion in 'Continuous Glucose Sensing' started by ecs1516, Oct 18, 2011.

  1. ecs1516

    ecs1516 Approved members

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    This only seems to happen on day 7 for us on the MM sensor. But, not every time though. We get cal errors on day seven and it then says change sensor. Never have cal errors on days 1-6. Any ideas?
     
  2. emm142

    emm142 Approved members

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    I think cal errors happen when the BG:ISIG ratio gets to a particular point (i.e. when the ISIG has dropped very low). I have had cal errors from trying to calibrate during a false low and from trying to use sensors once the ISIG has dropped a lot. Basically, it's generally a sign that I need to change the sensor.
     
  3. mom2ejca

    mom2ejca Approved members

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    Someone once posted a formula as a guide for avoiding cal error's, I think it came from someone at MM.

    Isig should fall within 1/2 to double of the Meter bg/ 10

    So for example, you shouldn't get a cal error with a meter bg of 160 as long as the ISIG value is between 8 and 32.

    I think using 10 as the divisor is just a general estimation of ISIG ratio. If you're keeping an eye on the ISIG ratio you could use that instead.

    So if I knew that the ISIG ratio early in the life of the sensor was around 8, and meter bg was 160, I would expect the ISIG to be somewhere around 20. If ISIG value on day 7 was below 10 (1/2 of 20) then that's a pretty darn good indication that there's a problem with the sensor.
     
  4. hawkeyegirl

    hawkeyegirl Approved members

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    I simply don't calibrate if BG is more than 50 points away from SG. I'll either wait until they're closer, or I'll restart the sensor. This is usually only an issue during the first 12 hours. With what you're describing, it sounds like the sensor is dying.
     
  5. ecs1516

    ecs1516 Approved members

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    I restarted the sensor and tried again later but it would give a cal error after entering a stable BG. I have a hard time getting 7 days out of these
     
  6. Diana

    Diana Approved members

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    I think the ISIG is just too low because the sensor is dying. Don't feel too bad - we only get 3-4 days before this happens.

    Restarting won't help if the sensor is really dying. I bet if you looked at the BG/ISIG ratio when this happens it would be well over 20.
     
  7. Tommo

    Tommo Approved members

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    We only get 6 good days from Minimed too...
     
  8. Snowbound

    Snowbound Approved members

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    Don't get that, but after seven days we get the lost sensor errors.
     

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