Calibration timing question!

Hi all, question regarding calibration. My son has a weird schedule and was hoping for some Dexcom calibration input.
He works Tues, Wed & Thursdays early so would calibrate at 6am then again 12 hours later at 6pm.
But on Friday & Monday he gets up much later for school and wouldn’t need to calibrate till 9am & 9pm. Then on the weekends it’s different again!

Are these time differences a huge issue? He’s a teenager and is burning out. I’m trying to help as much as possible and really don’t want to have to wake him up early on a weekend to do yet another test if I don’t have to.


You don’t need to calibrate the Dexcom CGMs at the same time every day. I think just following good calibration hygiene is the critical thing.

  • Only calibrate when the blood glucose line is relatively flat. A flat arrow should be considered essential. Missing a calibration is not as damaging as giving the system one when BGs are rapidly changing.

  • While Dexcom recommends calibration twice per day, fewer calibrations will cause no harm on accuracy.

  • Over-calibration does hurt accuracy.

Treating diabetes is a long game. You need to fit it into the life you live and do not need to adopt overly rigorous requirements.

The time differences you raise will not hurt the Dexcom performance.

1 Like

Thank you Terry4, we were under the impression we HAD to calibrate every 12 hours at relatively the same time! This is great news.

And thank you for your words of encouragement. Teen years are tough!

Agree with Terry.

I believe the wording from Dexcom is intentionally implying a “MUST” rather than “PREFER” due to FDA labeling issues.

Really it doesn’t matter. The only thing that happens exactly 12 hours after the last calibration is the warning or nag or icon or whatever your app/receiver has to indicate a calibration is due.
But when the calibration is due and if you are on an big upswing or big downswing (ie - rapidly changing BG) then you will CERTAINLY cause more calibration problems (read as in decrease accuracy) by calibrating RIGHT AT 12 hrs rather than waiting hours later for a level BG.

Bottom line. From a technical point of view, nothing special about the 12 hours. But that can be taken to excess. Do not calibrate every 30 minutes for example. Excessive. yeah - that causes problems.
But 8 hrs. 12 hrs. 16 hrs. whatever. No difference. When it is convenient and when BG is relatively straight and level.

I have a slight twist on this although certainly am basically in agreement. I would suggest doing the twice per day for the first 2 days (of a new session). After that, we find that has provided enough calibrations that “FOR US” (ie - each person needs to decide what works best for them) that one calibration every day or every other day works good enough.

EDIT: Also if using the G5 system and if using both the receiver (or integrated pump) AND a Smartphone app then you ONLY enter a given calibration into ONE of the devices. ie - ONLY enter a given calibration into the receiver (or integrated pump) OR into the Smartphone app. DO NOT enter the same calibration into both. Erroneously entering into both devices will count as two calibrations and will not provide ideal calibrations and subsequent readings from the G5 system.

(G4 operates differently)

Calibrations after the initial one isn’t required, folks! You can calibrate whenever your bgs are stable. You get a reminder from the receiver but you can click past it indefinitely.

He can just do it when he wakes up unless he thinks he’s gonna drop or spike then etc.