Penis tip dark

Q: I am 42; diabetic since 37 years; non-insulin type -2. of late I am noticing that the tip of my penis has become dark - in the sense it has become somewhat light black. Infact the tip I should say - with one inch diameter. What could be the reason? is it something serious? should I go to a doctor? has it got something to do with losing vigour? the rest of the portion is rosy.thank you for your time and in anticipation of reply soon.

A:It could be simply be due to drugs (Fixed drug eruption, Lichenoid eruption)or result of aging change. Exactly, it is difficult to say withoutexamination. Please consult a dermatologist.