I am planning to make cupcakes for a grad party the normal methods but I'm also going to make a grad cap cake and since some of the guests are diabetic I thought I'd make the cake sugar free. I plan to use pilsburys sugar free cake mix and frosting. My question is whether anyone has used pilsburys frosting to decorate like piping those little stars ect. I'm just worried if the pilsburys frosting is too soft or won't hold the shape if piped. I'd like to know if anyone's tried this and how it turned out then I can adjust my plans for decorating this cake accordingly. Thanks :)

would chocolate ganache be too sugary for a diabetic?

I'm not sure. I'll have to do a search for a recipe for ganache and check it out

Can you make some sugar free cupcakes as an alternate choice for people?  Some people will not touch an artificial sweetener with a ten foot pole because they are sensitive to these chemicals.  Artificial sweeteners can cause big time gastric distress in some people who can not digest them. 

At any rate, you should let people know that the cake and frosting is made with artificial sweetener because someone who is sensitive to the sweetener could end up with a surprise of unpleasant side effects if they unknowingly eat the stuff.  I am sure you do not want your cake to be tied to this sort of memory.   Heck, my own sister is diabetic and she refuses to eat these artificial sweeteners.  She will eat a slice of regular cake and usually will have one bite of the frosting and leave the rest on the plate.  You can plan ahead if you are diabetic as it is the carbs that count and not necessarily the form they take.