I wouldn't do that, it might be far better to do what you do and just keep it to yourself.
I found that challenging the advice I was given only resulted in conflict. Thy are trained to give the standard NHS advice and it would be a brave DSN who openly advised against it.
Many (mine included) will privately admit that the standard advice is not right for everyone, but do not forget that they are answerable to the doctors and many doctors do not fully understand T2.
You never know when you might need a friendly DSN, far better then to keep the DSN "on side".
I know it's frustrating, but I have learned to keep my mouth shut and nod politely, then do just what works for me
H