Both diet sodas and regular sodas add to your risk of diabetes, i'd steer clear of these if you have a family history.....companies are using better sweeteners in their diet sodas now like Splenda/Sucralose (which is made of sugar, they just take all the bad stuff out so it doesn't effect your blood sugar levels). Also watch the sodium amounts from the volume you are consuming, too much can cause swelling and that's just not good.
I drink diet sodas all the time, I just stay away from ones made with Aspartame.