Just substitute Splenda for sugar on a 1 to 1 basis. To try to duplicate brown sugar, add a small amount (like a teaspoon) of the darkest blackstrap molasses you can find.
Be sure to use Splenda, as it holds up to higher temperatures. DON'T use aspartame or any other artificial sweeteners.
And yes, I'm still on a low-carb diet. I'm also diabetic.
I highly recommend this book by Dana Carpender.