I mean actual sugar. Glucose signals your brain to refill the energy expenditure risk capacity. With ADHD your brain isn't normal. It's more active, it burns more and has less capacity for risk in energy expenditure (putting off reward). You need a steady stream of fuel. (Not a giant load, slowly sip on some orange juice or even lemonade when you work your brain). Look up Russell Barkley lectures on youtube. He's generally regarded an expert in the field.
Yo. And check out /r/adhd! You won't learn how to cope there, since everybody just shares their "successful" techniques that they got going for a week ;)
But it's super helpful to see how other people are like you, that it's actually not your fucking fault (pretty much saved my life...), that you're not lazy, and so on. ADHD also comes with a burden on your social life, from coming late, being impulsive and too easily aborting friendships (the radicalism on alleged principles, which I mentioned at the learning part) and so on, so it's good to untangle all that in the stories of others. Also that sub doesn't try to sell you ADHD as a blessing, which is good. You may "benefit" from divergent thinking and creativity at times, which come with the loose and jumpy focus, but ultimately it's a heavy burden, which has a toll on your life and health.
Daily exercise lifts your dopamine "base level".
However, if you really got ADHD you wanna try Ritalin, or Vyvanse. These stimulants work differently in ADHD brains than normal ones. To give you an idea: Some people take a small dose Ritalin right before bed, to calm their thoughts. I was skeptical about meds, but then I read in ADHD these stimulants actually "normalize" the brain as a long term "side effect". How often do you read that about psycho-pharmaca? They come at cost tho, of course, first medication I got with "sudden death" as a side effect... I also have trouble holding my weight (going too low), which started to scare me a little.