AIMS: People with type 1 diabetes have a higher risk for cardiovascular disease (CVD). Reduced heart rate variability (HRV) is a clinical marker for CVD. In this observational study using continuous HRV measurement across 26 days, we investigated whether psychological stressors (diabetes distress, depressive symptoms) and glycaemic parameters (hypo- and hyperglycaemic exposure, glycaemic variability and HbA(1c) ) are associated with lower HRV in people with type 1 diabetes. METHODS: Data from the non-interventional prospective DIA-LINK1 study were analysed. At baseline, depressive symptoms and diabetes distress were assessed. Glucose values and HRV were recorded daily for 26 days using continuous glucose monitoring (CGM) and a wrist-worn health tracker respectively. Multilevel modelling with participant as nesting factor was used to analyse associations between day-to-day HRV and diabetes distress, depressive symptoms and CGM-derived parameters. RESULTS: Data from 149 participants were analysed (age: 38.3 +/- 13.1 years, HbA(1c) : 8.6 +/- 1.9%). Participants with elevated diabetes distress had a significantly lower HRV across the 26 days compared to participants without elevated distress (beta = -0.28; p = 0.004). Elevated depressive symptoms were not significantly associated with HRV (beta = -0.18; p = 0.074). Higher daily exposure to hyperglycaemia (beta = -0.44; p = 0.044), higher average exposure to hypoglycaemia (beta = -0.18; p = 0.042) and higher HbA(1c) (beta = -0.20; p = 0.018) were associated with reduced HRV across the 26 days. Sensitivity analysis with HRV averaged across all days corroborated these results. CONCLUSIONS: Diabetes distress is a clinically meaningful psychosocial stressor that could play a role in the cardiovascular health of people with type 1 diabetes. These findings highlight the need for integrated psychosocial care in diabetes management.