Exercising a diabetic dog can be a very stressful process - especially with an unregulated diabetic dog.
While exercise IS important, too much can cause a break down of the stored form of glucose (called glycogen) which increases blood sugar.
We experienced this the other day. It was a beautiful day, the sun shining, kids playing in the street - just a great day. We took Buzz and Bella for an hour-long walk. The pups, used to our short 20-30 minute walk around the neighborhood all winter, were tired and hot at the end of the walk, something I didn't think this was a big deal as it had been more than twice as long as our normal routine.
I went to take Buzz's sugar about an hour later, and it was 'hi' (meaning over 750!). There was NO reason for his sugar to be that high, as nothing had changed. But wait, we took a longer walk - that was the ONLY thing that had changed... and certainly that couldn't have RAISED his sugar, right?
Digging back through all of the diabetes info stored in my brain over 3.5 years of graduate school biology classes, I realized that Buzz probably started breaking down glycogen (the stored form of sugar). Exercise should help the body absorb insulin (which essentially grabs sugar in the blood) so that the sugar is gone for good; however, too much exercise can cause a sharp decrease in blood sugar (the body was too good at absorbing insulin) and Buzz's body recogized that it needed to produce MORE sugar without eating, so it used its stored sugar. Weird, huh?
We learned the hard way that with an unregulated diabetic dog, you need to introduce longer exercise routines VERY SLOWLY. We won't be going on any more hour long walks for a while, but we will still be going on our daily walk (remember: exercise helps the body absorb insulin! which is great for a diabetic dog!). In the future, we will gradually increase the time we spend on our walk and hopefully can build his body's tolerance to increased exercise.