Background: Increased arterial stiffness may precede cardiovascular complications in patients with type 1 diabetes (T1DM). As the autonomic nervous system is responsible for regulating heart rate and vascular tone, autonomic dysfunction may contribute to increased arterial stiffness in patients with T1DM.
Objective and hypotheses: We investigated whether decreased heart rate variability (HRV) was associated arterial stiffness index (ASI) in patients with childhood-onset T1DM without chronic complication.
Method: Measurements of HRV and ASI, cardio-ankle vascular index (CAVI), were performed in 77 patients with T1DM (19.3±4.3 years, males 38 (49.4%)). Standard deviation of mean NN intervals (SDNN) and root mean squared difference of successive NN intervals (RMSSD) as estimates of overall HRV were obtained using a 5-min ECG recording using SA-2000E (Medicore Co. Korea). CAVI was measured using VaSera VS-1000 (Fukuda-Denshi, Tokyo, Japan). BMI z-score, history of smoking, duration of DM, systolic and diastolic blood pressure (SBP and DBP), HbA1c, HDL and non-HDL cholesterol were also evaluated.
Results: In youth with T1DM (diabetes duration 10.6 years (2.025.0) and mean HbA1c 7.9% (5.511.5)), CAVI correlated negatively with both SDNN (P=0.044) and RMSSD (P=0.032) and positively with age (P<0.001) and cholesterol (P=0.019). In multivariate analysis adjusting for demographic characteristics and traditional cardiovascular disease risk factors (age, sex, DBP, cholesterol, smoking, BMI z-score, diabetes duration, HbA1c), RMSSD were negatively correlated with CAVI (β=−0.049, P=0.024).
Conclusion: Reduced HRV, especially decreased RMSSD was independently associated with increased arterial stiffness in patients with T1DM. Early testing and treatment for cardiac autonomic neuropathy may be effective in preventing cardiovascular morbidity and mortality.
Funding: This study was supported by grant from the Seoul National University College of Medicine Research Fund 2013.