Dexcom G6 readings

Our latest unit is not giving accurate readings when we verify with finger prick. Sometimes a 40 point differential. Has anyone else had this issue?

Hi Was @dfwjwb, no I have NOT had this issue - but I only began using the G6 in mid-December 2019.

When, during the 10 day sensor-life, do you do your comparison checks? Timing could be an issue, as noted in the device documentation, during the first 24 hours. Also, “the lag time” between glucose traveling from blood into body tissue area and levels being read from interstitial fluids.

If you notice a particular timing of “differences”, please share; I’d like to attempt duplicating what you have seen.

@dfwjwb, I agree with @Dennis and I want to add the better time to check differences is right before a meal when your blood sugar is not changing quickly. That usually minimized lag. Also, beware of “compression lows” when you are sleeping on your Dex, I have not experienced this myself but it makes sense if you are squishing the interstitial fluid away from the sensor element.

also - if you stick your finger and see 190 mg/dl, your real actual blood sugar is most likely ANYWHERE between 210 mg/dl and 170 mg/dl (+/- 10%) and your cgm can read anywhere between 165 and 215 (a 50 mg/dl split) and it’s considered “good”. you will probably not get exact numbers between a CGM and a finger stick observation… you MIGHT… but you most likely MIGHT NOT.because errors are part of the game. If the total error “adds” as sometimes can happen, a total difference of 45-50 is not bad. your mileage may vary. good luck.

@dfwjwb. I only switched in the last month from g5 to g6 and thought I was getting large differences. In most cases, if I noticed a sizeable difference, my bs was changing more than I realized. I started comparing bg immediately and 15-20 minutes later. Almost always the readings were very close after that time if they were off initially. I DID have to correct one sensor once, but it was good after that.

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@dfwjwb the G6 sensor that I am currently wearing was off by 40+ points for the first few days. While the gentleman above is correct about the range readings may be in for fingersticks versus CGM, it adds a lot of guessing (and hoping it is right) to treatment. I had a “LOW” alert and I knew it had to be off because at 50 I start needing assistance to function. When I did a fingerstick, I I was at 93. I found myself calibrating often before meal times/during fasting periods until it came back to within 10 points on the morning of day 4.

I have noticed the site tends to play a role in the accuracy of my sensor. I generally do not have any issues with accuracy when placed on my abdomen or back. The back of my arms give me the greatest trouble.

Any time I have sensor issues or questions, I contact Dexcom. They are pretty understanding and willing to supply a replacement for issues - including inaccuracy! I think they have a threshold of 30 or 40 points before they declare it faulty (don’t quote me on that) and will replace the sensor.

I hope this helps and that you get it sorted quickly!

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Thanks for all the input. Our son is 8 and right now he doesn’t like the sensor anywhere but his arm. The sensor in question had already been there 5 days. We posted the question on a few sources, and one suggestion was to turn the monitor and/or our phones off, then back on. That actually worked.

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