Hi,
When my dog Max was diagnosed with diabetes one of the first things i was told was that he would go blind and that it would most likely happen in less then a year.
He was diagnosed over two and a half years ago and is not blind. He developed a small cataract in one eye early on but so far has not gotten any worse.
The thought of him going blind really freaked me out until someone on this forum posted a link that helped me understand how dogs "see" with their noses. It was very interesting and worth checking out.
https://www.youtube.com/watch?v=p7fXa2Occ_U