Start doing cardio (low intensity ideally HZ2 but don’t get focused on the numbers) when fasted. Ideally after like 18-24 hours of having fasted. You’ll force your body to burn fat and you’ll get more metabolically flexible, which means your body gets to handle sugar better (also crave it less).
If your BMI is above 25 this probably means doing long walks.
In the beginning you might get a bit dizzy (low blood sugar) but that’s the point. Don’t force it though and with time it’ll get better which means your body is adapting.
Also: don’t overdo the fasting etc. Prediabetic means that your metabolism isn’t running optimally, so a fast will be more difficult for you than someone else. Consistency is more important than numbers so don’t start “competing” with people with a different body than you.
Good luck!
Start small, do sustainable. On my 36 or 48 hour fasts I don’t feel like I need electrolytes. A few months back I had gone hard on the research and had all my electrolytes and started drinking them at the first hunger pang and it was too much and uh flushed out my system in a hurry.
So now it’s water and occasionally black coffee for me on fasts and I listen to my body on refeed days.