As used in sections 383.200 to 383.209, “insurer” includes any insurance company, mutual insurance company, medical malpractice association, any entity created under this chapter, or other entity providing any insurance to any health care provider, as defined in section 538.205, practicing in the state of Missouri, against claims for malpractice or professional negligence; provided, however, that the term “insurer” or “insurers” shall not mean any surplus lines insurer operating under chapter 384 or any entity to the extent it is self-insuring its exposure to medical malpractice liability.