The only time I use splenda is in my morning coffee, and that is because of a taste preference and too much pure sugar and I get jittery. Otherwise I don't eat anything that it's made with. No diet drinks, no diet foods made with splenda, etc.
I have to be EXTREMELY careful with anything labeled "diet" because I am allergic to aspertame. My mom drank it while pregnant with me and while nursing me, and it almost killed me. It is highly toxic to babies. And my mom did not over use it, maybe one diet coke per day or two.
Now, even the smallest sip of a diet coke (like the drive thru gives me diet instead of regular) and I have almost instant migraine. I drank about half a glass of diet lemonade one (without realizing it was diet, I thought the funky taste was because I had recently brushed my teeth) and I ended up with a horrible kidney infection. The Dr said if I were to drink even just two or three glasses of it, I probably would have gone into kidney failure.