Unfortunately, the military would not qualify him for duty. I ama 30 yro type one diabetic. I was diagnosed with type 1 diabetes while serving in the Air Force almost 10 years ago. As a result of my insulin dependent status, I was medically discharged adn I receive monthly compensation "disability" from the military as a result of it. I have since changed careers and am now a speech therapist. He can definitely be a police officer as long as he can keep up with the physical portion, but the military will not accept him.
Sorry =(
I suggest that you look at the answers to the question about whether a type 1 person can be a paramedic, for several people who posted there have researched police jobs also. Apparently, it is possible for a type 1 person to join the police force, at least in some cities (rules will differ, depending on the city, I suspect). As for National Guard, there might be different rules. He needs to actually contact the local National Guard recruiting office by calling 1-800-Go-Guard in order to find out the answer.