Characteristics of the sample.

Introduction
A correlation between health-related quality of life (HRQoL) and physical activity has been identified. Many studies have discussed whether this correlation is significantly associated with depression in the general and diabetic populations. However, the role of depression in this relationship, especially in individuals with diabetes, remains incompletely understood.
Objective
This study investigated the relationship between PA and HRQoL, with depression as a potential mediator, in individuals with diabetes.
Methods
This cross-sectional study involved 1,472 individuals with diabetes who participated in the Korea Health Panel Survey (KHPS) from 2019 to 2020. Their sociodemographic characteristics, PA, depressive symptoms, and HRQoL based on EuroQol-five-dimension (EQ-5D) scores were extracted from the KHPS. The mediating effect of depression on PA and HRQoL was investigated using multiple regression and a mediation effect test.
Results
HRQoL was positively associated with PA, regular exercise, and varying degrees of walking activity. Conversely, depression was substantially negatively associated with HRQoL. Mediation analysis confirmed that depression partially mediated the relationship between PA and HRQoL. Specifically, for PA and regular exercise, the indirect effect of depression accounted for 46.61% (B = 0.002, p < 0.05) and 33.82% (B = 0.003, p < 0.001).
Conclusion
In individuals with diabetes, depression was found to mediate the effect of PA on HRQoL. Therefore, conducting depression screening and managing depressive symptoms in this population is crucial to enhancing HRQoL through PA interventions. Consequently, strategies to enhance HRQoL can be effectively implemented and customized in response to particular depression screening outcomes.