Medicare and the ds

I called medicare last night and they stated that they did cover the DS. I need the DS as I have RA and take some NSAIDS(at times) and Methotrexate(all the time). I meet the qualifications, over 35 BMI and over 100 pounds. The surgeon I want to use is at a COE so okay there. I am concerned about the supervised diet as well as the co-morbidities. I think that since I have RA and arthritis they are considered co-morbidities. Any  thoughts on whether these would be considered co morbidities? Also, how long is the supervised diet for? Thanks! 

I am currently on ssd, and their guideline is 6month diet tried/failed rate.  basically you must show a diet tried for 6 months with a failed sucess.  hope that helps.