Your lucky in a way. I was also circumcised and getting erection and so forth is no problem. Only issue with me is that I don't ejaculate, I feel like I do but nothing comes out. Was told that my past uncontrolled diabetes has weakend the wall between the bladder. Which means my muscle isn't tighting enough when I ejaculate so the semen is going into my bladder and gets flushed out when I go to the toilet. Shame really... think a operation to tighten the muscle would do it but I'll worry about that when I want kids.
But yes, it's possible your issue can be linked to diabetes. Although, when you get circumcised you loose a lot of sensitivity on the tip so it could be that.