Physical Exercise Before Long-Term Electrocardiogram May Enhance the Assessment of Nocturnal Heart Rate Variability...

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.

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.

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).

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.