Your friend needs some education, but it makes sense that they say these things. ADHD, to the neurotypical mind, is a confusing and poorly understood thing. I like the above mentioned comparison to diabetes, and I might use that if anyone ever asks how my ADHD affects me.
I’ve been learning for a while not to try and use my ADHD as an excuse. I always use it as the reason for why something was lost/forgotten/missed, but I will then turn around and start fixing it because I know that my actions were what caused the problem. Unfortunately, my own wife (separated from her now, unfortunately) always saw my behaviors as excuses for why I didn’t get something done. No matter how hard I explained something to her, nothing could get her past calling my ADHD an excuse.
Don’t ever change who you are. But if your own struggles are bothering you, medication and therapy are effective (they are for me anyways). Remember: sticky notes can be your best friend. Take it easy.