Questions about calibrations and drift


I’ve been experimenting with xDrip+ combined with the Libre. Yesterday evening I calibrated once, at about 91 mg/dL. This morning BG meter said 96 mg/dL, but xDrip said 107 mg/dL. I recalibrated. Later today, I ate some pie, bolused for it etc. BG meter said 119 mg/dL, xDrip said 100 mg/dL. I recalibrated again. Now, a few hours later, BG meter says 97 mg/dL, xDrip says 109 mg/dL.

Now, I know that calibrating too often can be detrimental to the measurement quality. But, since I just started it, I figured I need to accumulate data points, so I calibrated more often to get a more robust calibration graph in xDrip. But now I am left wondering what tolerance range I should apply. I mean, up to how many mg/dL difference would you tolerate, and when would you consider it too far apart and in need of another calibration? 100<->119 , is this still okay for example?


can u move this thread to the appropriate forum section? Glucose Monitoring would be a better spot for it.


OK! Done.


I’ve been using xdrip at least 6 months and I use the OB1 collector. I also wear the receiver (for G5). Sometimes the two show similar numbers and other times, one or the other more closely correlates with a meter reading which I usually take no more than 4x a day and I don’t calibrate more than a time or two, per day except on day one, which is a mess. The G5 is all over the place for the first 18 hours or so so I will calibrate it frequently. Other than that, it is MY OPINION that calibrating more than once a day usually leads (with the G5) to more inaccuracies than it fixes. If a meter reading is lower, for example, than xDrip, I won’t enter the meter reading, but a reading higher by a few points, maybe 3-5, in order not to have xDrip then begin reading too low. It’s a thing u have to get a feel for, thru experience. If trend arrows are straight and it’s been quite a while (a day or so) since I’ve calibrated, if the meter reading is equal to, or just a few points different, I’ll enter the Xdrip reading as the calibration. I hope I’ve made that somewhat clear!!

If u use the Native Algorithm, u will lose some features, and it will match a Dexcom receiver or app’s glucose readings. I tried it for a while, but prefer OB1 Collector instead.


Keep in mind the BG meter can easily be off 15 percent - I would consider 11 points nothing