The rise significantly the first week then taper off quickly for 3 weeks

First question, why is back pain treated with steroids (and other medications)? It only masks pain temporarily without "treating" anything (the source/cause of pain). All back pain comes from mechanical strain of muscle/fascia and must be mechanically released to cure pain, much like tangled hair must be combed to untangle it, but not with medication. There is no concern of blood sugar related to one injection of steroids to the spine.