Traditional healthcare information systems (HISs) store patient information in their own clinics or hospitals in a decentralized manner. These healthcare systems rarely communicate with one another. Communication between health information systems has immense potential to provide personalized care based on historical patient information and customize individual treatments. The integration of patients with healthcare experts and their sharing of health information across healthcare systems prior to diagnosis helps enhance the quality of care by providing better treatment plans and recommendations. The effective use of personalized care with large language models plays a crucial role in making HISs more intelligent and improving the quality of care. This chapter aims to identify the challenges associated with implementing personalized care in LLMs and provide research directions for overcoming these obstacles and enhancing the effectiveness of personalized care in these populations.