My insurance also needed a health complication like diabetes, high blood pressure etc to be approved along with 6 months of weight loss. Due to needing the surgery as a revision to correct major complications from the previous surgery a disingenuous hack did to me, my insurance can wave the 6months requirements with medical proof of those complications. My new surgeon's office informed me that the insurance can backtrack my doctors visits for those 6months. My PCP and Gi are willing to send the necessary paperwork to my insurance telling them that the revision surgery is medically necessary due to the continued deterioration of my health.
What helped me a lot was a case worker from my insurance. Request one to assist you. They will collect all the necessary medical information that your appeal needs, a long with being an advocate for your well being.