Physical Exercise Before Long-Term Electrocardiogram May Enhance the Assessment of Nocturnal Heart Rate Variability in Young Individuals With Type 1 Diabetes Melltius.

BACKGROUND: Cardiovascular autonomic neuropathy (CAN), a serious complication of type 1 diabetes mellitus (T1DM), requires early detection for timely prevention of disease progression. Although traditional autonomic function tests effectively identify advanced neuropathic abnormalities, they lack sensitivity for early-stage CAN in young individuals. Heart rate recovery (HRRec) and heart rate variability (HRV) following exercise are potential early markers of autonomic dysfunction in this group. METHODS: HRRec and HRV from Holter-ECG recordings after a standardized exercise test were compared between 43 individuals with T1DM, aged 10-30 years, subject to modern treatment with advanced technology and with moderate to good metabolic control (mean HbA1c 57 mmol/mol), and 43 healthy controls, matched for age and sex. HRV was additionally assessed on a reference Holter-ECG recording without prior exertion. RESULTS: Twice as many participants with T1DM (33%) compared to controls (16%) maintained a heart rate > 100 beats/min beyond two hours after the exercise test. HRV did not differ between groups on reference Holter-ECG without prior exertion, but nocturnal HRV was significantly lower in the T1DM group compared to controls after the standardized exercise test (p < 0.05), primarily among individuals with a lower physical capacity. Long-term HbA1c correlated negatively with nocturnal high-frequency HRV in T1DM participants (p < 0.05). CONCLUSION: Heart rate variability post-exercise may be a pertinent tool for the assessment of early autonomic cardiac dysfunction in young individuals with T1DM with moderate to good metabolic control.