For the vegetarian make some pasta and add sauce with no meat. If you make your sauce with meat, buy a jar with no meat and toss it on his/hers.
The diabetic with wheat intolerance is another matter.
The diabetic knows what, and how much, to eat, so I will dismiss that (been there and I know).
The wheat intolerance means no pasta, I would think.
But I would get about the whole issue by making a great anitpasto.
Easiest thing in the world to put together and folks can pick and choose.
Jarred or canned srtichoke hearts, cheeses, meats, olives, pimento peppers, pickled mushrooms, heck, just walk about the market and find what you want to serve.
Did this one Christmas and no one wanted us to cook the steaks, they all were sated.
Just an idea. Merry Christmas.