About the best I could find when it comes to type 1 diabetes was someone saying that a plant based diet had helped reduce the volatility of their blood sugar levels. No mention of no longer needing insulin, or their pancreas magically repairing itself. Nothing that would make the device in the OP substantially less helpful.
This is all hardly a surprise, because plant-based diets tend to be low in refined carbohydrates, large quantities of which make diabetes harder to manage. People have achieved similar effects eating lots of other diets that aren't too high in carb (and this is, indeed, one area where mainstream science on the subject is in the process of updating itself).
Please, tell me of the people with type 1 diabetes who have had their condition reversed by a change in diet. I'd genuinely love it if it were true, but it's not. It's complete BS.
By the way, calling something 'mainstream' when it comes to medicine is not the insult you seem to think it is. It generally means 'credible people have performed studies with a credible methodology, and they have found stuff out'. You'll have to forgive me if I don't find anecdotes on the internet a particularly compelling alternative.
This is not to say that fringe opinions are all bad - occasionally one of those opinions will be right, the mainstream will be wrong, and the mainstream will be updated. Usually, though, we try to have some kind of credible evidence before stating wild leaps as fact - because most of these fringe opinions are wrong.