Another natural sugar substitute that you might want to try using in your sauces is "Agave Nectar". It's a thick syrup, made from the same plant as tequila is made from. It's becoming very widely used instead of sugar and you won't be able to detect the difference in the finished product.
PS. It's suppossed to be ggod for hypogluacimics as it does not alter your blood sugars(follow up on that).