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Are these readings real or is the Dexcom broken?

Discussion in 'Parents of Children with Type 1' started by Charlotte'sMom, Aug 23, 2012.

  1. Charlotte'sMom

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    This is too weird for words. I've attached the pictures of the 3, 6 and 12 hour Dexcom screens. I put in a new sensor last night before she went to bed, which is why the 12 hour screen starts where it does.

    When the Dex was ready to be calibrated, I put in both readings of 110 and 118. When I checked her 2 hours later she was in the 100s again with 2 arrows down, and she had this huge spike up into the 350s. I've never seen a rise and fall that big within 2 hours. (She had dinner IOB, but got no correction for that spike) I gave her a couple ounces of juice, but she didn't have any IOB by the time I checked her the 2nd time so I didn't think she'd keep falling. The rest of the night went the same, with another huge spike into the 300s, and smaller spikes up to 200 and back. I heard the Dexcom alarm a couple times in the night because it said her bg was falling. (she never got below 100 though) and when I checked her with the meter it was pretty accurate. I never corrected for any of those spikes, because I didn't see them until the after the fact. I only woke up to the falling alarms.

    I haven't changed changed her nighttime basal settings in a while. And the last 2 nights she had beautiful, steady, in range overnight numbers. So I was feeling pretty awesome about these basal settings.

    But this? What in the world is this?
     
  2. Charlotte'sMom

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    I didn't treat that 119 when she was a falling this morning. A couple minutes after I took that picture the arrow switched to straight across like she was holding steady. Now the screen (at 6am) says she's 165 with double arrows UP! :confused: The meter says she's only 121.

    ETA: At 6:20 the Dex says she's 216, but the arrow disappeared. Meter says she's 128.
     
    Last edited: Aug 23, 2012
  3. selketine

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    So when you say she was this or that number - this is the Dex and not a finger stick for the wild swings up high right?

    It could be a bad sensor or perhaps it could be from the pressure of sleeping on it. I don't think it would necessarily mean the hardware was bad.
     
  4. Charlotte'sMom

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    Sorry if that wasn't clear. The huge spikes I only saw on the Dexcom. When I've tested her with the meter she was in range, but by then the Dexcom was too.

    This is how the morning has gone since I woke up.
    5:30am
    Dex - 119 2 arrows down
    Meter - 118

    6:00am
    Dex - 165 two arrows UP
    Meter - 121

    6:19am
    Dex - 218
    Meter - 128

    6:25am
    Dex - 124 (and I didn't calibrate. Dex got this number on its own)
    Meter - 128

    6:40am
    Dex - 90 and 1 arrow down
    Meter - 132
     
  5. tiger7lady

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    Are her basal settings overnight the same or do they go up and down all night?

    I'm thinking it was how she was laying on the sensor. Sometimes when my son lays directly on it we get some really weird readings from the Dex but as soon as he's not laying on it the Dex is right in line with the meter.
     
  6. Charlotte'sMom

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    Her basals settings don't go up and down during the night. But they do start out higher and at about 3am they are the lowest compared to the rest of the day. And like I mentioned, the last 2 nights she was really steady overnight.

    I've seen the Dex be off now and then, but there's so many of these huge spikes throughout the night it makes me think it's more than just the way she was laying. After watching her morning meter numbers, I don't think any of those huge blood sugar spikes were real.
     
  7. tiger7lady

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    It might be a bad sensor/bad location. I would watch it for the next day or so during the day and see if it's way off from the meter.
     
  8. swellman

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    I have seen spike like that and sometimes I attribute them to lying on the sensor.

    The only way to tell is to set a high alarm and check when it's high. Where's your high alarm?
     
  9. Charlotte'sMom

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    I turned it off the other day when she was at school b/c she had gotten a correction for the high bg, but I didn't want it to keep beeping for the next 30 minutes while she came down. I just never turned it back on. I can't say for the spikes during the night, but this morning she had one last spike up to 200+ and I know that was wrong because I tested her with the meter several times and she was fine.

    I suppose laying on her sensor would make sense. But 7 different (presumably incorrect) bg spikes throughout the night? Even after Charlotte got up and was walking around this morning it was saying 80 and arrows down, when I was fairly confident from her last meter reading that was still wrong. I didn't test her again after I bolused for breakfast and she ate.

    I didn't feel comfortable sending her to school with her Dex having that kind of error. So I took it off and put a new sensor in. I figured having no Dexcom (since it takes 3 hours to get ready) wasn't any worse than an unreliable one while she's at school. Hopefully Dexcom will replace the sensor. :(
     
  10. swellman

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    Well, if you tested and the meter and the dexcom do not agree then it's obviously something going on with the dexcom. Sometimes we get wonky calibrations and the dexcom seems to be "overly sensitive" meaning the direction of the data is correct but the sensitivity seems way too high so the highs are way too high and the lows way too low.

    If that happens and it doesn't sort itself out we restart and if that doesn't help then we switch sensors.
     
  11. Charlotte'sMom

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    I didn't even think to just restart the sensor. I changed it out completely. Doh.
     
  12. Kayeecee

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    Sounds like this was a brand new sensor with only one calibration. We almost always have crazy readings the first night of a new sensor, much as you've described. Which is why we never count on the readings that first 12 hours; they rarely match the fingerstick. And our sensors usually go on to synch up beautifully in the next 24 hours or so.
     
  13. selketine

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    Our readings aren't usually that terrible on the first 12 hours of a new sensor but we have had a sensor (I remember one in particular) that was very wonky the first 12 hours and settled down and was great after 24 hours. Whenever it got pressed on the readings would plummet - then go double up when it wasn't being pressed on. This seemed to make it go higher than it should too.

    It was put in the typical location - just must have been something wonky about it the first day.

    I agree next time to leave it in and restart or give it at least 24 hours to settle down. Of course if you have a good amount of sensors and they aren't too precious to use then changing it out really is fine too.:cwds:
     
  14. Charlotte'sMom

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    Well, I'm (kind of) relieved to hear that this isn't completely abnormal. We've only had the Dex for a few months, and I have never seen anything like that before. Every once in a while it'll be off, but to go up and down like that repeatedly was a little shocking. I've heard people say the first 12 hours are sometimes unreliable, but I've never felt like they were way off.

    FTR, it was on her arm. We go back and forth between her arms and her stomach, and I've even felt like her arms work better than her stomach. Usually. :confused:
     
  15. swellman

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    I used to think the same thing but we have switched to the stomach and have seen much, much better stability and accuracy.

    I suspect it was because the arm is so lean that we were inserting into muscle - the sensor wire would come out bent at crazy angles and accuracy and longevity were spotty. Now the wires come out perfectly straight.

    It's still not perfect but I think it's much more reliable from a trending POV and the accuracy is as good as I can hope for - mostly.

    We did go through a box of sensors that all failed pretty quickly or at startup. They diagnosed the transmitter as bad and we had the entire system replaced through insurance but we still had a sensor failure. I think it was the sensors but I'm happy with the new receiver since it's crazy loud.
     
  16. Charlotte'sMom

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    She's got enough meat on her arms I feel like it's been okay. I try to use her arms so we can rotate pump sites on her belly. I don't want to put pump sites on her arms where the tubing is going to visible. I had a niece yank on it once and we've never put it there again. But for some reason I don't mind the Dex there.
     
  17. maciasfamily

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    We almost always get wonky number the first day maybe even to 2nd day of a new sensor. I pretty much won't take anything it says at face value and always check with a BG.

    If you're seeing such crazy numbers, I'd leave it alone for the rest of the day into tomorrow. Keep calibrating as needed but don't remove.
     
  18. Michelle'sMom

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    Those unreliable first hours are the reason we insert at night & wait until morning to start. My dh starts the sensor at 4:30 when he gets up. By the time it's ready for the first calibration she's up & ready for breakfast, so the BG is stable. Evening calibrations fall before dinner, so another good time. It's worth going 1 night without readings for the accuracy we get....we rarely have readings more than a couple of points off from the meter.

    We had 2 sensors early on that gave readings similar to your pics. Both were inserted too close to the muscle. The sensor wire was bent almost accordion-like on one. The other one was painful when she moved, & actually broke off when we pulled it.
     
  19. Dan

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    I have also had similar issues with some of my sensors. I normally will enter a BG wait 15 min then enter a second BG. This normally fixes the problem. When it does not I call DexCom tell them what I tried and they always send me a replacement sensor.
     
  20. Melissata

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    It should only take 2 hours for a sensor to be ready to start, not 3. We have seen crazy numbers and arrows like this during the first 12 to 24 hours occasionally. If it doesn't get better, we stop and restart. That usually fixes things. I have learned not to trust the sensor at all for the first day, and she always tests before treating a high blood sugar, and never strictly from the Dex reading, at any time. We will treat lows without testing though.

    The other thing that you may want to change is how often you get an alarm for a high blood sugar. We have hers set to 2 hours so that she doesn't want to keep correcting. There is no sense having a constant reminder of a high that you have already corrected for and are waiting for the insulin to do it's work.
     

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