D.M.
Our pedi, whom I'll miss since he's retiring, never sent Eldest out of the room when it came to talk about her meds. In fact, she's been answering most of the questions since she was around 7. We were lucky that our pedi was also a behavior specialist (whom also had ADHD), as well as our local EFMP (Exceptional Family Member Program) specialist.
Honestly, a good doc will talk to the kiddo first, then get the parent's take on it. This happens after awhile though, because for starting the doc needs input from both to make an informed decision.
Hiding this from your kiddo, will only instill the idea that something's wrong with him, or that he's broken. That it has to be hidden at all costs. That's actually very counterproductive to helping him manage himself later on in life.
We've been open and honest with Eldest about this since day one. Now she's at the point where if she misses a dose, she knows the tricks to keep herself focused and not climbing the walls, and also knows when to speak up and let everyone know she thinks her meds aren't working for her anymore, or when she needs a booster or minor tweak.
Taking this approach, we've been able to keep Eldest on an extremely low dose. 36mg Concerta. She's in high school now, 5'4" and 119 lbs. That dose shouldn't be working for her according to the "charts" but it is, because we've helped her learn about her condition, and taken steps to help her with additional focusing exercises like breathing techniques.
Good luck!