Re: bobble head cat??
I'm new to the forum, so I don't have a good idea of Teddy's history. I assume he's diabetic, currently being treated with insulin? Head tilting can be a sign of low blood sugar, which is a serious situation, and I'm worried that the head bobbing might be a for of tilting. There's a great tab above on hypoglycemia that might help you decide.
If you've checked his blood sugar and it isn't low, then it might be a form of diabetic neuropathy, although I'm only familiar with the form that causes difficulty in walking properly. With all the people on this forum though, there might be someone out there who has seen something like this in their own cat.