Hi Scott!

Is your doctor an endocrinologist? If not, you might consider asking for a referral to one or just going to see one on your own. I think an endocrinologist would be much more likely to agree to a circulating insulin test than a GP or internist. An endocrinologist would also be much more likely to be up on all the latest information regarding diabetes (hormones are their specialty, after all) and how all the different hormones work together.
Just something to consider....