A diabetic can get a First Class medical with a waiver. I'm diabetic with type 2, and although my medical is currently not a Class 1, it was issued that way.

It's obviously not a desired plan, however.

I have to submit "blood work" once a year. Since it can take 60 days for FAA approval, you really need to start the process after 9 months, which will leave you with a 30 day "buffer". I don't really need a First Class, but I get one anyway and let it lapse into a 2nd class.

You get a letter from the FAA that states you can have a Class I,II, or III, but it will have a one year limit, which goes on your certificate.

So after six months, you can renew your First Class medical, but another renewal requires the submission of a doctor's report listing certain blood levels, and other items.

So diabetes doesn't automatically remove you from a medical, but it's certainly a lot better if you eat properly and avoid, if at all possible, type 2 diabetes.

Class 1 is more of an heredity issue, I believe.