A friend of mine came down with type II. He asked his physician if he could take long bike rides. His physician essentially said "I dunno" but when he found out that there were three of us, proposed the following little exercise.
Three of us were cycling buddies. So he brought his glucose meter. The idea was that he would take our blood sugars at the start of the ride (it was 70 miles or so) and once an hour after that. At the start, the diabetic type II's blood sugar level was higher than the controls. After an hour, the type II blood sugar was lower than the controls. Everyone's blood sugar was lower after riding an hour but the controls had not gone down much. To make the story a bit shorter, the type II blood sugar kept declining as the ride progressed. The controls did not or if they did, the decline was not meaningful.
Now, I rode with this guy once a week and on a 70 mile ride (well usually). He had a cheerful disposition. One day we got back, we had started at my house, and he was really crabby. He was finding fault with all sorts of things that I had done or not done as the case may be. I gave him a hard look and said "stand right there and do not do anything". I went into the house and got about 4 ounces of orange juice and brought it out to him and said "drink this now". He drank it and within a very short time was "himself" again. This episode was repeated a few times over several years. Now, I understand that diabetes is a pretty individual thing. Typically, this guys blood sugar would keep declining even if he ate snacks but the decline would slow significantly. He told me that he could eat a "snickers bar" on a century without ill effect. Also he told me that he did 4 days of long rides and on those days, he could eat anything without ill effect.
If you have some buddies who do not mind a finger prick, you might try to round up some "controls" for your own study.