Are you receiving a benefit under the life-course savings scheme before taking normal or early retirement? In that case you are not entitled to Dutch-funded medical care in your country of residence. You also cannot retain your health insurance in the Netherlands.
That means you need to arrange health insurance yourself in your country of residence. However, as soon as you start receiving a statutory pension, you are entitled to an S1/121. You can apply to us for this using the S1/121 application form (7.12.2020, PDF, 758 kB).