Hi. Not for diabetes, but my cat was there several years ago for myesthenia gravis. They were wonderful! I met with several different doctors all on the same day. I had to spend the day, and go back after lunch to meet with someone who wasn't available in the morning, but this was my cat, of course. They kept him there for me while I went to lunch.
Sorry, I don't know what questions to ask or anything like that for your problems, but I was very pleased with all the attention Max was given, and the degree of caring I saw in the doctors and staff.
Parking wasn't a problem, either, on the days I was there. We went back over and over. Make sure you take a carrier, of course. There are lots of people there and dogs. You will want to get there early, because it is a big building, and it's confusing to try to figure out where to go -- even how to get into the building. The entrance is near a courtyard, and is not apparent from the parking lot. I suggest that you call and ask them exactly how to get there, and how to get from the parking lot to the office you are going to. No need to stress with your cat being all freaked out after the car ride, etc.