I am also a T1 diabetic, and I am athletic. I find that after a hard work out or an intense run my BG will be elevated, however it will drop with out notice after the spike too... I think this is due to the adrenalin as well as the release of Glycogen from the liver durring stress.
Yes, I agree that adrenalin is the culprit. And this is probably safer for you than having your sugar levels DROP during a fire, which could endanger you and the men you work with. I know that we hate to have to do anything different or to be treated differently, but if you need to take a 2-minute break during a particularly bad fire to test your glucose and administer some insulin to bring sugars back down, that may just be something you need to build into your routine. The only other option is to know to test as soon as the fire is over and to take some insulin at that point, knowing that your levels will be elevated for a few hours until you are abole to check it and to compensate. I am not aware of any way to prevent this from happening. The adrenalin dump is important to you to keep you safe.
I had mentioned to a friend with a diabetic son that after I exercise(run) in the morning my blood sugar will sometimes shoot up 100-150 points and this is after a reading of 120-150 prior to running on my treadmill. I then have readings that are 200-250 and I get very frustrated! I am a type I diabetic for 26 years. I thought this was strange seeing that I had not eaten anything to make my blood sugar climb so high. She told me her son's endocronologist said that sometimes adrenaline can make your blood sugar rise. Maybe you could do some research on adrenaline and blood sugars rising. I had never heard of this before, but it makes sense. I am thinking that being a firefighter would take alot of adrenaline and would be stressful too. Stress makes my blood sugars rise very high too. To prevent this I don't know-but again ask your endocronologist and do some research and I will look too-if you find something out I would be interested in the answers too.