When making a type of fondant the use of corn syrup is common. The formula I use is 8 ounces of corn syrup, 1 lb of powdered sugar and then mixing in granulated sugar until stiff, you can also mix in some pollen if you like. In that mix you are giving the bees fractose, frutose, and glucose.
Since feeding sugar or fondant is more the exception than the rule using a little corn syrup is okay. I agree that a steady diet of the stuff isn't so good for the bees.