Just to add a little to the discussion regarding artificial sweeteners I have just read an article on the subject where a scientific study had taken place on sucralose (Spenda).
It found that on some obese people who has not used it regularly before it can raise blood sugar and insulin. To quote
Bottom Line: Sucralose may raise blood sugar and insulin levels in people who do not consume artificial sweeteners regularly. However, it probably has no effect in people who regularly use artificial sweeteners.
Makes me feel a little better as I use it all the time although it was a small study.