The health care transition for adolescents and young adults (AYAs) with Type 1 diabetes, a condition arising from insulin deficiency due to beta-cell destruction in the pancreas (American Diabetes, 2018), poses a significant challenge. Globally, more than one million children are affected by this condition, with approximately 130,000 children newly diagnosed each year (Tuomilehto et al., 2020). Most children diagnosed with Type 1 diabetes transition from adolescence to adulthood, and their numbers continue to rise in tandem with advancements in medical services (White & Cooley, 2018). The adolescence of AYAs with Type 1 diabetes involves experiencing difficulties in blood glucose control. Simultaneously, they undergo physical, psychological, and social changes, including the exploration and adaptation to societal norms and roles, peer influences, changes in family structure, and a shift in responsibility from parents to oneself (Xie et al., 2023).

The American Academy of Pediatrics recommends preparing for healthcare transition from early adolescence, starting at the age of 12(White & Cooley, 2018). Health care transition is defined as “the purposeful, planned movement of adolescents and young adults with chronic physical and medical conditions from child-centered to adult-oriented health care systems”, Successfully navigating this process is crucial for maintaining diabetes management and establishing a disease management system in adulthood (Blum et al., 1993).

In the case of adolescents diagnosed with Type 1 diabetes during childhood, parents initially take full responsibility for diabetes management. However, as independence and responsibility increase in early adolescence, parents gradually transfer some of the responsibility for diabetes management to the adolescent. Subsequently, the responsibility for diabetes management is shared more equitably between parents and adolescents, and by the late teens, the locus of diabetes management shifts from parents to adolescents (Gardener et al., 2022). During this process, Moving away from a relationship of complete dependence on parents during childhood, adolescents seek a new balance in their relationship with parents to achieve psychological independence during adolescence (Tuohy et al., 2023; Turin & Drobnič Radobuljac, 2021). In a previous study that proposed an integrated theoretical perspective combining Transition Theory and Bioecological Theory, it emphasized the necessity of considering health care transition and adolescent developmental tasks together(Joly, 2016). Psychological independence from parents is a crucial developmental task for adolescents with chronic illnesses, contributing to a successful transition into adulthood (Joly, 2016; Moon, 2020). To ensure the successful transition of adolescents, there is a need for parents to embrace the developmental process of adolescents and redefine their roles to enable adolescents to manage their health independently. However, a significant challenge lies in the lack of awareness regarding this, highlighting an important issue (White & Cooley, 2018; Wong et al., 2023). Parents of AYAs with chronic illnesses often continue to exert excessive control and involvement due to their past responsibility for long-term disease management, even if the AYAs can manage their illness independently (Zhou et al., 2016). Such cases can lead to missed opportunities for AYAs to take control of their health management and increase the risk of an unsuccessful health care transition (Badour et al., 2023). Moreover, in contrast to Western norms, many Korean families are characterized by a strong, unbreakable bond between parents and children, making it challenging for adolescents to achieve independence (Kim et al., 2019; Moon, 2020). Although psychological independence from parents is one of the important developmental tasks, there has been no study confirming the relationship with health care transition, so it seems necessary to confirm this.

Adolescents diagnosed with type 1 diabetes aspire to independently manage their health and perceive the transition of healthcare responsibility from parents or healthcare professionals to themselves as a natural and desirable part of their growth process (Strand et al., 2019). Health locus of control refers to an individual's generalized expectations regarding who plays the most proactive role in managing their health. It influences the development of an individual's health behaviors (Lau, 1982). Positive preparation for health care transition is influenced by a strong belief in an internal health locus of control, where individuals believe their health is under their own influence. Conversely, a belief in an external health locus of control, where health is influenced by external factors, has a negative impact on transition readiness (Nazareth et al., 2016). However, despite recognizing themselves as the agents of their health management, many adolescents often express challenges in blood glucose control, experiencing diabetes complications, including hyperglycemia and hypoglycemia, due to misjudgments. This poses an increased risk of long-term complications (Strand et al., 2019). Consequently, repeated investigations are imperative to substantiate the correlation between health locus of control and healthcare transition.

Guiding AYAs through the health care transition preparation process is a crucial task for health care professionals (Gleeson & Turner, 2012). Many institutions have highlighted the importance of continuity in health care transition and have advocated for long-term transition programs for optimal clinical care (Tuomilehto et al., 2020). However, evidence and resources related to health care transition processes and information are still lacking, often leading to unprepared and abrupt transitions for many AYAs due to a lack of education and training (Dwyer-Matzky et al., 2018). Additionally, there is a lack of interest by medical professionals in health care transition in Korea, and research in this area is scarce(Kim et al., 2019; Kim & Yoo, 2021).

To effectively evaluate and offer suitable interventions for healthcare transition readiness, a comprehensive, multidisciplinary approach is imperative, centering on key factors such as the individual, family/social support, environment, and the health care system (Betz et al., 2014). Among these, this study specifically focuses on individual psychosocial factors, aimed to investigate the influence of psychological separation and health locus of control on the readiness for health care AYAs with Type 1 diabetes, a representative chronic condition. Thus, it is crucial to identify factors influencing transition readiness by examining the correlations between these factors to provide foundational data for developing health care transition intervention programs and nursing interventions that can assist successful health care transitions for AYAs with Type 1 diabetes in the Korean medical environment.