First off... Good For YOU!
From other threads here on DF I think the general consensus is that there is no "cure"... you may have reversed your symptoms to a much earlier stage of D and they may never reappear; so long as you maintain your improved habits BUT it is unlikely you could eat freely as before without D rearing it's ugly head again.
In terms of insurance you might even see a new Doctor and pass an A1c and Fasting BG... possibly even an OGTT... BUT (and I could be wrong) I suspect the insurance terms are carefully worded such that if you have EVER been diagnosed with D then it is a pre-existing condition. I would not be surprised if they employ investigators to search out "false claims" as a reason to deny payment.
On the other hand you have dramatically improved your chances for living a much longer and healthier life