Predictors of Exercise Performance in Type 1 Diabetes: The Role of Hypoglycaemia Fear, Glycaemic Control, and Vascular Health: A Retrospective Cross-Sectional Study.

AIM: Cardiorespiratory fitness is often impaired in individuals with type 1 diabetes. While physiological determinants have been studied, psychological barriers such as fear of hypoglycaemia remain underexplored. We hypothesised that glycaemic factors including HbA1c, diabetes duration, the presence of microvascular complications, and fear of hypoglycaemia, would predict lower exercise performance.

METHODS

This retrospective cross-sectional single-centre study included adults with type 1 diabetes who participated in a multidisciplinary rehabilitation program at the University Medical Centre Groningen. Outcomes were oxygen uptake, power output and heart rate at ventilatory thresholds and peak exercise. Predictors included age, sex, BMI, smoking history, diabetes duration, HbA1c, microvascular complications and fear of hypoglycaemia. Analyses comprised group comparisons and stepwise linear regression.

RESULTS

This study included 122 individuals with type 1 diabetes (median age 33 years; 76 females). Median HbA1c was 75 mmol/mol [IQR 63-93]. Hypoglycaemia fear survey data were available for 106 participants (median Worry score 23.5; Behaviour score 20.0). Higher HbA1c was negatively associated with VO2 at second ventilatory threshold (β = -0.085) and peak VO2 (β = -0.089), as well as power output and heart rate. Greater fear of hypoglycaemia predicted lower power output at second threshold (β = -21.95) and peak exercise (β = -28.97). Microvascular complications were linked to reduced heart rate at ventilatory thresholds, with stronger effects for multiple complications.

CONCLUSION

Fear of hypoglycaemia, HbA1c and microvascular complications are key determinants of reduced cardiopulmonary exercise performance in type 1 diabetes, highlighting the need for integrated physiological and psychological interventions.