I've been swimming with my pump (Animas Ping) for about the past month. I've also been having super high blood sugar pretty regularly. Usually at least once a day I will test after a meal and be 17-24 (300-400+) on a random basis, almost like I missed a bolus except that I didn't. I limit most of my meals to 20-30g of carbohydrates, so it's not like I'm usually eating crazy stuff.
I've noticed the past few times I've changed cartridges (when my pump is empty) that the cartridge smells very strongly of insulin and has moisture around the outside. I wonder if swimming could do something that makes the cartridges leak? Either that or maybe it's a wonky package of cartridges. Could it be some problem with the pump itself? I've never swum with my pump before, so I have no idea if swimming could affect it like that.
I also thought maybe the water was just pool water, but again, I don't know. If the cartridges are leaking intermittently it would certainly explain some of my highs (but I know the pump is working because I also have good blood sugars as well as lows). My blood sugars tend to be crazy regularly anyway, so maybe it's all just changing seasons/hormones/activity levels, too.