A comparative study of anxiety levels and its relation with heart rate variability (HRV) indices in adolescents with type 1 diabetes mellitus.

Aim: The aim of this study was to see correlation between anxiety levels and heart rate variability (HRV) indices in adolescents with type1 diabetes mellitus (T1 DM).
Methods: Sixty four subjects were recruited for this study which included 33 patients with diagnosed T1 DM and 31 controls. All the anthropometric measurements such as height, weight, BMI and biochemical parameters were recorded. Subjects were invited to the autonomic function testing laboratory (AFT lab), in the department of Physiology, for HRV analysis and anxiety level determination using a simple questionnaire called Hamilton’s scale of anxiety (HAMA). Statistical tests like unpaired T test, Fischer’s exact test and Pearson’s correlation coefficient was employed where ever necessary.
Results: Anxiety levels were negatively correlated with percentage of Normal-Normal interval pNN 50 (r= -0.380,p< 0.05), Standard deviation of normal-normal interval SDNN(r= -0.349, p<0.05), root mean square of the squared deviation RMSSD(r= -0.384, p< 0.05), very low frequency VLF(r= -0.586, p< 0.01), low frequency LF(r= -0.048, p< 0.01), high frequency HF( r= -0.351,p < 0.05), total power (r= -0.468, p< 0.01). Anxiety level was positively correlated with LF/HF ratio (r= 0.349, p< 0.05). There was no correlation between anxiety levels and biochemical parameters such as fasting blood glucose and glycated hemoglobin (HbA1c).
Conclusion: Since HRV is a marker of parasympathetic activity, a negative correlation of anxiety levels with HRV parameters indicates reduced parasympathetic activity in patients with T1 DM. A positive correlation between anxiety levels and sympathovagal balance (LF/HF ratio) appears to be because of reduced parasympathetic activity which is attributed to reduced HF. It may be concluded that in this preliminary study anxiety appears to play an important role in reducing HRV in patients with T1 DM.