[i_cannot_hack]

Well, if you wanted to match the glycemic load of a diet soda you would have to drink 100% less, i.e. not at all, not 'slightly less'. Drinking less sugary soda is not a comparable alternative to drinking diet soda, even if you prefer it. So saying diet sodas are pointless on that basis seems a bit non-sequitur. Also consider that 10% of the US population has type 2 diabetes, and almost 40% are prediabetic.