I have found out that my policy does not cover the gastric sleeve surgery. But I'm wondering if my doctor were to write a letter to the insurance company on my behalf explaining my health issues, etc if that would make any difference? I need all of the help/information I can get.

Yes, If your doctor writes you a letter of medical necessity, with extensive documentation Aetna MAY approve the procedure. but you may be looking at increased pay on your end; Aetna most likely will not cover the entire procedure, and if they do cover some of the costs, your out of pocket payment may be higher than someone else under another aetna plan that covers the procedure.

it's worth a shot to try