If you you use Vetsulin brand of insulin for your pet you should read this.
FDA?s Center for Veterinary Medicine Alerts Veterinarians About Problems with Vetsulin® to Treat Diabetes in Dogs and Cats
Not my yorkie but my Mini Schnauzer has been using it since March 09. I almost lost he in October. She went hypoglycemic and was having a seizure. He blood glucose was so low it didn't even register on my meter. I put honey on her gums and roused her enough to eat but she was very disoriented and her legs would slide out from under her. She had to lay down to eat. If I had not been home when this happened I wouldn't my Missy Ann. Oh, there had been no changes in her diet or insulin.