sudden vision problems in diabetes type 1 patient

Hi, my friend is 46 years old and he is suffering from diabetes type 1. He complained several times in last few months that his blood sugar level is high in spite of therapy he is using. Yesterday he called to tell that he experienced sudden vision problems and he couldn't see anything for a moment. I told him to visit his doctor as soon as possible. I would like to know what might cause such disorder.

Hi, I am suffering from diabetes for very long time. Diabetes affects blood vessels and makes them stiffed and filled with calcium. This may cause poor supplying of nerves and neuropathy because of that. Same thing is with optical nerve which may be damaged by diabetes and it may cause vision problems to your friend.