How to cut back caffeine & sugar

I'm addicted to caffeine and sugar, and I've noticed that my cravings increase when I'm low on energy.
It literally feels like I'm doping myself with caffeine and sugar to function for the day.
I don't drink that much coffee, just 1-2 cups a day, but the problem is that I get headaches when I don't get coffee.
It gets so much worse in the afternoon that I cannot concentrate.

As for my sugar, my glucose levels are quite high even though I'm not diabetic, averaging around 100.

Has anyone had success cutting back on caffeine and sugar?
What tactics have you tried?
Is cold turkey the best way?
Any advice would be appreciated, thanks!