Following up as promised following Blu's vet visit and his neuropathy as it seems are cats have similiar experiences...
The vet did a range of motion exam, and according to her, his flexibility wasn't awesome but not awful, basically age appropriate. She thinks he might have a bit of arthritis mixed in with the neuropathy.
She supported the B-12 supplement but also recommended another supplement along with it called Cosequin. She said she has seen results from it both with diabetic-related neuropathy and age-related arthrits. They are the gel type tabs that you can open up and sprinkle the product right on the food. (hate pilling cats!)
Here is the link to it on Pet Meds
http://www.1800petmeds.com/Cosequin+For ... OgodTxYAcg
She added that patience is a virtue with neuropathy, some cats improve quickly once sugars are regulated, but she also said MANY cats need 3-6 months of regulated sugars to see the best results in terms of improvement.
Might be worth asking your vet to check range of motion and see his/her thoughts on the Cosequin. Oh, the vet said she thinks it is the glucosamine in the Cosequin that really helps in conjuction with the B-12. She said that there are other cat supplements that have glucosamine in them but can adversley affect blood sugar so her preferred brand for a joint health supplement for cats with diabetes is Cosequin.
Anyway, others here may have better/more advice, I'm just sharing what the vet said in case it offers any insight.