Sorry Sarge, but I think you're SOL. You might be able to stay in the Guard by being in permanently not deployable status, depends on your CO and job function. Getting hit with the big D diagnosis is not easy to handle, but you have to think not only of your well being, but also of your grunts. They could have a rough time of it if you went big time hypo or hyperglycemic at precisely the wrong time.
I'm service connected for DMII, Agent Orange. I enjoyed my time in the Air Force. Got up to S/Sgt in special ops flying around in C-130 Talon's. In that job, diabetes is an automatic kick out. I hope that your unit will need and appreciate your service back here in the States.
Something that you need to do pronto: get copies of ALL your medical and service records and keep up-to-date copies of future records. Those records have a way of getting lost - for years.
Best to you and yours