(a) No group accident and sickness insurance policy, other than policies of disability income insurance and credit accident and sickness insurance and other than policies of qualified self-insurers, shall be issued in this state, which policy limits or restricts payment of benefits for any preexisting illness or condition not otherwise excluded from the group policy for a period in excess of 12 months following the date of the issuance of the certificate covering the insured person.

(b) This Code section shall also apply to policies issued by a hospital service nonprofit corporation or a nonprofit medical service corporation.