Is there a way to create diagonal guides in indesign, just like in illustrator. Is there a plugin which can do this?
Not directly, and as far as I know, no plugin either.
Sometimes I set up a non-printing layer when I need a diagonal guide... because the Line Tool can draw diagonal lines just fine when you hold down Shift. All I really need out of my guides is that a) they should not print, and b) stuff should snap to them (if I have Smart GUide Options -> Align to Object Edges checked; this is checked by default). So this works for me for those one or two projects every year where diagonal guides would be helpful.
If you need something beyond that, then my solution would probably won't work for you.
But objects don't REALLY snap to them the same way they would with a guide. They snap instead to the bounding box for the diagonal line and it's centerpoint.
I said to myself "Inconcievable!" and then went and tested it. But you're completely right. I am lining up a gradient with a "fake diagonal guide" (to make some "fake folder tabs" across the top of a ten-language poster I do every year) and it's actually snapping to the top and bottom. It's certainly snapping, but not to the guide. #thatsmetold
Well, it's not like the method is completely useless, as long as you understand the limitations.
I've been known to do similar things myself.
This has been a requested feature on indesign uservoice for several years now: Turn paths into guides with the right click menu "Make guides" like in Illustrator.
If you scroll down the comments Bob Rubey shares a link for a script that will convert objects to guides. The link is broken, but a simple search will come up with this link: http://kasyan.ho.ua/indesign/all/convert_object_to_guides.html
Objects still will not snap to the objects like they do with guides.