I took microbiology this last semester. If you look at the ingredients, under carbs, something like manitol is still a sugar, but it's not you're traditional C6H12O6, so the teacher said it can be called sugar free, but it's still a sugar.

I'd try to determine that the hidden carbs way (calories minus 9 times grams of fat minus four times the sugar, divide answer by 4 to get hidden carbs)