Nothing usually, however Starbucks Specialty drinks, (basically everything) use flavored syrups in their coffee. Much like what you would see at an ice cream place. They do have some sugar free syrups (I get a skinny vanilla latte that is made with skim and sugar free vanilla) but I have yet to see anyone else order what I do, with the exception of a few of my shitlord friends.  You can click here if you would like to see what I am talking about. Its one of Starbucks' site where you can purchase the same syrup they use in-store.