Strange jumps

Check out these three images and see if anything looks wrong…

This happens infrequently, but lately it’s been happening more than usual. What it causes is a) confusion on mine and Erin’s part b) total panic c) extra “calibrations” which add to our calibration overall count…we had been around 3 and since this has happened 4 or 5 times this week alone (doesn’t usually happen so frequently), we’re up to 9.9 calibrations on average/day for this week.

The 252 was displaying as “double arrows down” while the other two numbers were “level”.

97 Level at 13:48

Suddenly, 252 double arrows down at 13:53

Erin had to reset calibration (enter it twice to set it back to what it actually was…73, at 14:08)

My guess is that somehow the tape around the sensor got a little dislodged and then the sensor jiggles about to produce those weirdo readings??? We have also gotten strange stuff like that when the sensor part got a little wet – the part under the transmitter.

Has this happened with multiple sensors or just this one?

The other night we had a really wonky set of readings – sensor reading LOW and 40 sideways arrow down, and then we tested and he was 155… then the sensor basically had a hissy fit and shut off for a while and when it came back it read HIGH – and he was 230. So that was a sign to change the sensor.

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Tape is fine and in tact, the sensor is affixed tight against the skin. He’s not gotten it wet since we changed it out (changed it yesterday early morning).

Yes - just not as many as we’ve gotten this week, with this sensor.

We have these kinds of issues when we haven’t calibrated when we should…if we don’t calibrate an hour or two past the time the calibration drop appears (such as when we’re sleeping and the blood drop appears), the numbers can be WAY off… > 100 off, sometimes even > 150/200 off.

Typically when our sensor session is coming to an end, we can always tell because the receivers start skipping dots…once that skipping start (communication failing), we change it out.

It’s really wonky!

I have seen something like that a few times. I talked to Dexcom and they gave me some specific instructions on re-calibrating it which were not the normal calibration steps. They said if it is X percentage off of your BG test, to redo two calibrations X minutes apart.

And they said if it happens X number of times within X number of hours, replace the sensor.

I don’t recall the specifics. I don’t remember all the “X’s” they told me. :slight_smile: So maybe worth a call to them.

This is exactly the sort of thing that makes me leery of the closed loop stuff…


@ClaudnDaye, we have seen a few of these: they always seem to be related to a physical event with the sensor for us. So, when they happen, we just discount them and recalibrate.

Is it possible that Liam has been more physically active lately, possibly banging his sensor around more often?

I am a bit taken aback but your average number of calibrations. This does seem quite high. Ours hovers around 2 because my son is frequently unable to do a second calibration in a day due to too many peaks and no flat section in the curve at a time with no IOB.

It’s been such an insane afternoon / evening…

Here’s a bunch of images to show what’s been going on today since before lunch…I would say maybe it was the changeout of the new sensor, but as you’ll see by the first image, he was riding smoothly the past 24 hours. We changed it early yesterday morning and it was perfect for the first 24 hours. I would think if it’s a whacky sensor, we’d have known right off? I really don’t want to do a change-out…he hates them still. So confused and frustrated at this.

It’s times like these that I am going to get in my TM state of mind and go read my previous happy posts to reflect on those good times. :smiley:

The images all have text within them so there won’t be any separating them.

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Ours is usually at 3. Every week it’s 3. This week it’s almost 10. Because of the reasons cited in this post…huge jumps and drops in BG from what the CGM is reading to what he actually is. Having to re-calibrate many times because it’s just been way off. But his BG’s are definitely acting strangely as I indicated in my last post.

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We get this stuff every once in a while.

I would say it’s part sensor, part site and part blood sugar – and that treatments based on the trends from the Dexcom can exacerbate the crazy…

Usually the BGs really aren’t that crazy, but they’re changing a lot more quickly or unpredictably than usual (maybe because the site isn’t so good or he’s getting sick or something) and Dexcom basically just makes up random stuff in order to keep up.

My theory is that when a site is bad, you sometimes get erratic “squirts” of insulin hitting the system in a way you normally wouldn’t, which can create sharp drops and also unexpected highs.
When we have those lags – say he’s in the 60s, just not rising for like an hour, and then all of a sudden jumps to 140, etc, that means the sensor is dying, or he’s getting sick.

When this lasts long enough, I just change out the sensor, or the site. It could be placebo effect – i.e. his blood sugar was going nuts, and then by the time we realize the issue and change out the sensor, whatever physiological cause for the weird jumps disappeared, so it seems like it was the sensor change that caused the positive improvement. But at least it feels like something you can do that’s proactive to get ahead of the nonsensical nature of the readings.


Harold, this is a pretty shocking curve. I did not want to comment on it yesterday because I was tired and it looked so chaotic to me. But I am looking at it today again and it still looks chaotic as heck. I can’t really find explanations that make sense ::scratch head::

  • Beyond the original 2-dot bandit, it appears the CGM was functioning very well, only doing normal Dexcom artefacts. So this all appears to be real BG changes.

  • Is it possible that he smuggled in some food around 7:45pm? It is hard to understand this spike – although, with us, it would just be a puberty spike. I am mentioning this because this happens to all kids at one time or another.

  • Is it possible that his basal is too high by 20% or more? There are a lot of downward trends along the whole picture.

This looks like a day of h*ll to me.

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No, he’s not big enough yet to access food on his own – unless we leave stuff out (which we don’t do). It could be one of those growing things…I know we’ll need to be prepared for many of those to come.

His basal rates are correct. .05 some of the day, .10 the other parts of the day when he tends to ride higher.

This is what’s so frustrating about diabetes, to me. You never really figure it out…there are millions of times when you will think you do have it figured out, but then the disease shows you that you really don’t. Perhaps when they are older and (hopefully) flat-liners…but pre-adult, it’s a constant game of “Gotcha, No you don’t.”


Agree with this completely!


I would disagree about whether these are real trends. I mean, I do think the sharp spikes and drops are real in their overall trend…but it seems to me that Dexcom is overestimating and lagging on both ends of the curve, meaning the timing and absolute value of these rises is off, which is part of what contributes to the craziness. But obviously looking at past Dexcom curves and trying to make sense of them is like looking at inkblots and trying to find meaning – you can interpret whatever you want in them :slight_smile:


I have no doubt you are right there. But from Harold’s finger testing, it appears that the Dexcom was right on after the transients: beyond the usual 10-15 minute delay, and the usual transient Dexcom issues, it seems that the data presented by the CGM is essentially what happened in this case.

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