Congrats on your decision to take control of your health. It's so important.
I'm a little confused as to why your BMI does not already qualify you for surgery? Did a bariatric surgeon tell you that you needed to be "diabetic" or was that your family doctor? If not a surgeon, I'd try to get to one to find out what else might qualify you for surgery. There are other co-morbidities, like hypertension, heart disease, sometimes sleep apnea, that also qualify you (along with BMI).
I think you have to just start working the process, and it can sometimes be a long and frustrating one. But, working the process is good preparation for what you need to do post-surgically and beyond. So, it's good practice.
The other thing I would advocate is be honest with the surgeon and team, but also be persistent. Sometimes, the "squeaky wheel gets the grease" and you need to demonstrate how committed you are to this. That will often help to get you the documentation you need to meet the insurance requirements. Sometimes they also consider previous diet history and how well/poorly you did with that. My insurance had me go through 3 months of weight loss counseling/effort pre-surgery. Some require longer than that. Just stay positive and persistent.
Best of luck to you and keep posting about your efforts and their results. People will respond to you and provid you with suggestions....they definitely will. You are not alone with this.