I got back in the pool this morning for a swimming technique class which I had been goint to quite regularly before new year. I’d like to say it was good to get back in the water. But I don’t think I will ever be able to say that about swimming. So I got up checked my sugar which was hovering around 200, I ate a banana with some globs of almond butter on it and off I went. That’s right I didn’t bolus for my banana at this time, I was going to be swimming in half an hour after all! I got to the pool and gave myself a quick bolus of 0.5 units to cover the banana and no insulin during the swim.
Guess what? I got to work and it was over 300 yowza’s!!!!!
Repeat after me: swimming is not like regular exercise; swimming is not like regular exercise. Yes that is right ladies and germs, sometimes the anticipation of the swim and being in the water has the opposite effect of other types of exercise (especially for those ahem, who will you say are not as comfortable in water). In hind site I should have timed the bolus better, but I’m particularly cautious when it comes to swimming and error on the side of high (but not that high!)
Seriously, I am not that anti-swim otherwise I wouldn’t be doing it. If you are a diabetic (or not) and you are thinking about swimming as exercise don’t let my little mishap deter you. I 100% support swimming as a way of keeping fit especially since it is low impact! Swimming can also be very soothing and good for your soul, so quiet and peaceful. Just test before, test after and keep some form of sugar handy! If you have a pump that is not waterproof like mine always take into consideration the fact that by removing your pump you will be without insulin for as long as you are swimming for. You might want to try a waterproof pouch. I use an aquapac for my really long swims. http://usstore.aquapac.net/ If you go that route keep in mind that you may need to reduce your basil rate, I do, some people may not need to. Also, if it is open water I stick a gu in my wetsuit or swimsuit. Doing drills or long swims can make your heart race which could be mistaken for a low. All the issues can be resolved but every now and again you slip up and that is ok.
Endurance Diabetic 
+1 on this. Swimming definitely doesn’t cause my BG to drop anywhere near as much as running or cycling. I think its because I’m very much still a newbie to swimming – so theres still a lot of anerobic thrashing around, rather than nice smooth aerobic swimming. I’ll generally try and get in the pool around 130 or so and have maybe 15g carbs from a sports drink before starting a session. That generally leaves me in the 90 – 110 range finishing up. Might have to change this a bit once we start doing some open water swims where it won’t be as easy to check BG and take on carbs if needed. Its possible the anxiety of OW swimming could send the numbers through the roof too!