That's a fair point. I wonder what percentage of accidents are cuase by diabetics v. (say) heart disease or some other medical condition? I don't know the answer, but it might shed some light on the issue.
The problem with simply denying a license to diabetics is, first of all many of the wild episodes you hear about happen before people are diagnosed. Many people are diagnosed as a result of an episode that makes it obvious something is wrong with the person. My sister was a nurse, and was diagnosed when one day as she was leaving the hospital after her shift, she simply walked off the side of a loading dock type entry at the rear entrance of the hospital, instead of taking the steps. Luckily she was not seriously injured, but about 5 minutes later she would have been behind the wheel of a vehicle in traffic.
Also after diagnosis and proper treatment, many diabetics never experience a crisis with their blood sugar again. Those that do may be years in between events.