I have hoy been pumping a short while and it may just be me, but just before I went on the pump my doses had all quite dramatically dropped -probably the warm weather...however over the last week or so I've been climbing and I've had to up my basal by about 40% at some points in the day! and also my carb ratios have come down by a similar amount. I am back to being quite peaky after meals too (do all the wait and eat and low GI etc).....anyway with that the corrections that I have been taking have not been bringing me down by the 5.2 for 1 unit that I was initially set up at (in my opinion) so I googled the rules on ISF and on that basis my ISF should be around the 3.8 mark, so I've changed it to 4 for tomorrow but may chicken out of such a drastic change and start with 4.5 just to be safer. Is ISF something that you find you have to play with much? Should you adjust it as your doses change for either hormones or weather or just cos your diabetes decides to do those changes?