I had a sense that reverse corrections were not working for us and now am very concerned about how our PDM is calculating them. In many cases, it suggests a bolus that I believe is .05 u. lower than it should be -- in all cases when there is no IOB. I noticed this late Saturday afternoon when DD's BG was 85 and she had a 12 g. snack and no IOB. At that time, her Target is 120, I:C ratio 1:50, and ISF 1:200. The PDM suggested 0.00 u. correction. By my calculation, she should have received a 0.05 u bolus: Reverse correction of -0.15 (rounded down to the nearest .05 u) BG - Target / ISF = Reverse Correction (85 - 100) / 200 - -.18, rounded down to -.15 Carb Bolus of 0.24 12/50 = 0.24, rounded down to .20 Total Bolus -.15 + .20 = .05 u In checking the CoPilot software, I see this happening nine times in the last 10 days or so. In each case there has been no IOB (it's been easy to check as I check DD's BG on waking and bolus her for 8 g. gummi vitamins). I called Insulet who gave me the name of a CDE in my area who is supposed to be able to explain this, but I am going to wait until I also have DD's PDM in hand to double check the calculations shown there against the Co-Pilot download (though the example from Saturday was one I noticed and refigured using the PDM). Given DD's low insulin needs, 0.50 u [ETA: should say 0.05]is a meaningful difference. Now I'm wondering if there could be an issue with our PDM, this is not complicated math, so I don't understand how the PDM would be doing this calculation differently.