# Omnipod: auto-calc by PDM or manual bolus calculations? **URL:** \ **Category:** Pump\ **Tags:** omnipod\ **Created:** [January 4, 2018, 4:25am UTC](https://forum.fudiabetes.org/t/omnipod-auto-calc-by-pdm-or-manual-bolus-calculations/3088 "2018-01-04T04:25:29Z")\ **Posts on this page:** 1\ **Showing post:** 21
**Author:** ![Michel](https://yyz2.discourse-cdn.com/flex030/user_avatar/forum.fudiabetes.org/michel/32/387_2.png) [@Michel](https://forum.fudiabetes.org/u/Michel)\ **Post date:** [January 5, 2018, 7:29pm UTC](https://forum.fudiabetes.org/t/omnipod-auto-calc-by-pdm-or-manual-bolus-calculations/3088/21 "2018-01-05T19:29:05Z")
> [@ClaudnDaye](#): > > Have you or anyone else experienced that the longer you go without calibrating your CGM after the blood drop appears, the further off the readings become? What an interesting comment! It actually ignited some reflection in me. My son has a lean body right now, and we often have a hard time getting a sensor to last. When I think of accuracy, we have several cases that come up: - About half the time or more, our calibrations are within a very small number of units of actual. It often is associated with a specific sensor, where strings of calibrations always seem good—but not always. - About a third of the time, a calibration is about 15 off, and the calibration result will halve that. It does happen quite often that these come in strings too, where, everytime with calibrate a sensor it is 15 off. These strings appear to progressively drift away, but others don’t always drift continually with time (although the all do, just not with a steady rate) - A small number of times, we are way off. In that case, I will often do two calibrations within a half hour or so. It is quite rare to be that far off many times on a row. I have experimented a few times, and forced a calibration on a sensor (twice the same number) when it is somewhat off, by averaging two or three fingerprint measurements and force-entering the result. It has several times resulted in a tack-sharp follow-up calibration. But my number if samples is too small to be reliable. --- _[View the full topic](https://forum.fudiabetes.org/t/omnipod-auto-calc-by-pdm-or-manual-bolus-calculations/3088)._