I don't know about diabetes and fasting, but I do know that type 2 diabetes is 100% reversible by correct nutrition, see video. If it's type 2, best advice is to become undiabetic, then do your fast (for whatever reason) without meds. The healthy eating will also better prepare yourself for a fast.
If it's type 1 and you want to fast, someone else can answer your question. I don't know anything about fasting and meds, apart from the fact a true fast does not involve meds.