Database Tuning Advisor user permissions
From BOL : Permissions Required to Run Database Engine Tuning Advisor


  After you install SQL Server, a user who is a member of the sysadmin fixed server role must launch Database Engine Tuning Advisor before anyone else. When the sysadmin user launches Database Engine Tuning Advisor that action initializes the application for use by others. After Database Engine Tuning Advisor is initialized, any user who is a member of the db_owner fixed database role can use it to tune tables on databases they own. For more information about initializing Database Engine Tuning Advisor.