How do you explain limitations?

Hi Everyone,
I am new to this site and a recently diagnosed diabetic. I am struggling daily to understand my new way of life. I am wondering, how do I get through to people that I shouldnt (I dont like "cant") consume food or booze in the same way they do? I have a lot of well meaning people in my life but they cant seem to understand that me eating a load of carbs or fat etc isnt what I need to do to remain healthy. I feel like I’ve said it enough but I must be saying it wrong, they just dont get it. Thanks

ps- any reading or tips suggested for my new lifestyle is appreciated!