I’m not on Medicare, but I’ve read posts that say Medicare has strict rules about pump and supplies. Must see doctor every 90 days, and doctor must submit specific notes regarding your treatment. You might find other posts on this, or you could start a new one, or others can comment here.
@Terry4 may have details specific to Medicare, although may vary by state.
Once you know the rules, some doctors seem to have good staff/procedures that make it painless, others describe the experience as a constant PITA.
Here is older post on medicare/doctors notes.