No colas (diet or otherwise for me). Water or coffee. Not in that order. I have cut down my consumption of coffee from two POTS a day to 4-5 cups. I match them one for one with big glasses of water.
I have been eating healthy since my diabetes diagnosis several years ago. At least I was wise in one respect. Being mildly OCD, I plan my menues for the entire day. No excuse for me to stray in that respect.