I think one of the things that annoys me a bit about articles that go on about how great exercise is for diabetes is that none of them talk about how HARD it is to manage in terms of blood sugar!
Tonight I swam 1 km in the pool. It took around 30 minutes (hard to tell exactly, as I didn't have a watch and can't see the clock).
At around 6:00 I tested at 4.2 mmol/L (76 mg/dl) and ate a few glucose tablets. At around 6:30 I set a two-hour temporary basal of -30%. I also ate a 10g dinner with no bolus.
At around 7:30 I tested at 5.7 mmol/L (103 mg/dl) and ate two glucose tablets.
At 8:00 I was 8.5 mmol/L (153 mg/dl) and swam for 1 km.
I felt terrible while swimming, not from diabetes but from asthma, I think ... after the first 150 m or so I could barely breathe and had zero energy. I had stupidly forgotten my inhaler at home, but swimming takes so much effort to pack and catch the bus and change and pay the $6 (!) drop-in fee that I didn't want to call it off. By the end I had a headache and felt sort of dizzy. I felt like I could have swum more but felt like it was probably a bad idea when I couldn't breathe properly. Even after stopping the wheezing lasted a good hour or so before finally going away. Next time I will for sure use my inhaler before going and also mention it to my doctor if I feel so horrible again while swimming.
At around 8:45 I finished swimming and tested at 5.7 mmol/L (103 mg/dl). Unfortunately I had to wait an hour for the bus because I missed the one I intended to catch. At around 9:30 I tested at 7.7 mmol/L (139 mg/dl) and took a full correction.
Then I got home and tested at around 10:45 ... and got 15.4 mmol/L (277 mg/dl). I had been feeling like maybe my blood sugar might be perfect (this is the first time I've tried wearing my pump while swimming), but alas, it was not to be. But at least I didn't go low!
In the past I've tried taking my pump off entirely for swimming, which has always ended disastrously ... blood sugars of 17 - 20 mmol/L (300 - 350) and ketones of 1.0 - 1.5 (normal is 0.0 - 0.5). This time around ketones were 1.1 (that's equivalent to large) with my high blood sugar. I truly don't know how people can suspend their pump or take it off during exercise. I don't know if it's too little insulin causing this (I thought so when I disconnected, but now I'm thinking maybe not) or something else about swimming that triggers it.
Anyway, I just did a 4.0 unit correction and will be up monitoring ... Some reward for exercising, high blood sugar, ketones, and staying up half the night. Hopefully I won't crash overnight. I'm taking tomorrow off, but I would like to make swimming a regular event three or so times a week. So I should get to try again in about two days.