Sometimes the best way to deal with something is to agree to disagree. The truth is, no everyone can be convinced to see things the way you see them, or understand them. Some people either choose not to understand or just can't for whatever reason.
You've got to put these people on certain levels. A friend like that, who either refuses or can't understand what I'm saying, I will refrain from discussing my bipolar with them. I have a co-worker friend who I think has bipolar. But she doesn't believe in seeing psychiatrists or Ts at all, both culturally and spiritually. So after I realized there was no way I could convince her to talk to her issues with a doctor, I just dropped it. She will tell me how she's feeling and I just listen and let her know I understand. That's all I can do.