We had a dog (Cica) that became diabetic. Shortly after that diagnosis, she went totally blind (diabetic cataracts). We had her lenses replaced, and it's the best money we ever spent.

She did fine on twice daily injections. We had a hard time trying to get her blood sugar regulated at first. Human glucometers don't work reliably in dogs. Once we got an AlphaTrak veterinary glucometer, we dialed her in quickly. For us, it was easier to check levels at home, and learn to adjust the insulin dose. She had a crazy high dose (25 units twice daily). The cost of the glucometer was offset by all the vet visits we didn't have to pay for.

It is possible that Henry wasnt diabetic when you adopted him, and developed it after you got him home. Cica developed it quickly. Regardless, I'm glad you're taking care of your boy.