It is the same as any other substance, fine in moderation. I can't remember the safe dosages exactly off the top of my head but you're fine to consume it. I will post a link to some studies when I find them again sir.
Although Splenda may not penetrate the blood brain barrier as do other substances, hence entering the brain and creating neurotoxin havoc at the brain center, Dr Janet Starr Hull says, Splenda can still adversely affect the body in several ways because it is a chemical substance and not natural sugar. Use it with caution!
I am a diabetic, type 2 borderline. I never used sugar in my coffee or tea, so I did not have to give it up. I use Splenda on breakfast cereal and it works fine. No ill affects so far. You can find web pages stating otherwise, but the FDA has not issued any warnings.