The aim of this study was to assess the relationship between physical activity (PA) level and depression, anxiety, quality of life, self-esteem and HbA1c in adolescents with type 1 diabetes mellitus (T1DM). Methods: A cross-sectional study design, including 41 adolescents with T1DM and 38 healthy controls aged 13-17 years, were included in this study. The PA level was assessed using the Physical Activity Questionnaire for Older Children. Anxiety was screened using the Screen for Anxiety Related Emotional Disorders questionnaire. Depressive symptoms were evaluated using the Children's Depression Inventory. The Pediatric Quality of Life Inventory 4.0 was used for evaluating the quality of life. Self-esteem was assessed using the Rosenberg Self-Esteem Scale. Results: Emotional functioning of parent proxy-report was significantly lower in the T1DM group (p=0.01) compared with the control group. The PA level was positively low correlated with the Pediatric Quality of Life Inventory 4.0-child self-report (r=0.48, p=0.03 for total scale score; r=0.49, p=0.001 for the physical health summary score). There was a low negative correlation between the PA level and HbA1c (r=-0.40, p=0.01). Conclusion: The present study suggested similar PA levels, depression and anxiety scores, selfesteem, and quality of life (except lower emotional score in parents' proxy reports) between adolescents with T1DM and healthy controls. The PA was associated with quality of life-adolescent self-report and HbA1c in patients. Despite similar PA levels, these patients should be encouraged to adherence to PA in the early period to improve the quality of life and metabolic control.