I started on diet drinks a few years ago to get away from high fructose corn syrup. My cholesterol problem went away when I stopped gulping down large amounts of high fructose every day.
My high blood sugar went away as soon as I stopped drinking Dr Pepper. Now I drink diet green tea instead of any other liquid, and have been doing it for maybe ten years. I have low blood pressure and staying hydrated helps. It’s easier to drink the green tea, with its anti-oxidant properties, than chug a lug water.