What Causes This?

I was at day 10 of a G5 sensor and everything stable in the 90s.

All of a sudden dropped 13 points and 5 minutes later increased 10 points. Then became stable again and two days later still ok. Was sitting on the couch so not compression. What can causes these sudden changes in readings?

Hi RCA -

My guess would be that It’s a Dexcom issue. The technology is wonderful but is not 100% accurate. On top of which I think a g5 is rated for 7 days not 10.

If those things concern you, check the reading with a finger stick meter and see if it’s a measurement issue.


So the basics of a sensor are an electrode covered with glucose oxidase and a few outer coatings. It could have been a transient change in the local area, i.e. the tip moved slightly into a different local tissue environment, or it could have been an actual change in the area around the sensor, like you drank some water and now the flow of interstitial fluid changed. Hard to guess really, but we observed things like that happen often with the G5, less so with G6.


Chris, that’s the kind of explanation I was looking for. At the moment I think it was a "transient " change. I am on day 11 of sensor but have gone up to 5 weeks once so I figure sensor is a failure if I have to change within 7 days.

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I’ve only had experience with the G6. Mine does the same thing as @rca221 reports with the G5, although I think everything happens inside the transmitter. When the sensor is older (particularly at 10-14 days) the transmitter will report a sudden rapid drop then a corresponding rise back to somewhere around the original level. This typically takes three to six readings - 15 to 30 minutes. I don’t feel anything physically and it happens more frequently as the sensor gets older (it doesn’t happen much, if at all, during the recommended lifetime). Normally the transmitter will start reporting sensor errors a day or two after this happens.

So far as I know the G5 and G6 have basically the same sensor technology, so it wouldn’t surprise me if the G5 does the same thing.

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