Just to throw in a slightly different point of view -- I'm diabetic.
Fibre has no impact on blood glucose levels (BGL) and therefore does not need to be counted when figuring your carb intake.
Sugar Alcohols do have varying degrees of impact on BGL (depending on the version involved) and need to be counted - on average - by half. Other artificial sweeteners are not entirely without BGL impact either, and for some super-sensitive people, can have negative effects, too. Splenda (for example) is considered calorie-free when used a teaspoon at a time -- it is actually about 1/2 carb, or 2 calories per tsp -- but if you are cooking with it, you should count it as 24 carbs (96 calories) per cup. Nothing is really "free", I guess
However, when compared to sugar at 192 carbs (770 calories) per cup; it's a pretty good deal.