I have an almost 13 yr old Bichon who was diagnosed last January ( of 06' ). It was similar for us, he lost a lot of body weight in a short time was urinating and drinking alot. I had no idea dogs could be diabetic. He had been starting to lose his sight and now he only has about 5% vision. Anyway, once we got him regulated on the insulin, he started to act like his old self again and has adapted very well to loss of sight. I think it is harder on us than on them. The first month or so was hard, getting him to eat, and testing his blood glocose (at the vet) to find the proper dosage of insulin. But, he is doing very well. If you have any questions about it pm me or check out this site for canine diabetics:
http://p090.ezboard.com/fpetswithdiabetescaninediabetes