I am so sorry to hear about Beau losing his vision from diabetic cataracts. My name is Rebecca. I am a veterinarian and will do my best to help.
It sounds like you have good control of his diabetes, if his BG is 127.
Topical flubriprofen ointment may slow the development of cataracts, as might the supplement Ocu GLO. The Can-C drops are worth trying as well. I checked my resources, and a well know veterinary ophthalmologist ( she literally "wrote the book") has not found the Can-C to make a difference. I think these products may slow the progress of cataracts, but no drops or medication yet know restores sight that has been lost because of cataracts.
Surgery is the best way to remove cataractrous lenses, but it is expensive. Prices vary depending where you are. In my area, surgery for both eyes is around $5000.
I am sorry she is scared, bumping into things and depressed and that is understandable. However, blind dogs do learn to cope and can live a good quality of life if cataract surgery is not possible.
Please let me know what other questions you have.