 Other Part C sponsors include non-profit charities under their respective states' laws, and/or are under union or religious management.However there is no rule against insurance companies sponsoring Part C plans and many do.A more common involvement of insurance companies with Part C is to act as the administrator for the non-profit sponsor (the best example being the relationship between the non-profit AARP and UnitedHealth - a health market conglomerate that began as an insurance company).