Features of short-term heart rate variability in internally displaced people with type 2 diabetes mellitus

Background. Internally displaced people (IDP) often face many problems, both physical and psychological. Anxiety and depression inherent in IDP predict slow recovery and increase the risk of post-traumatic stress disorder and mortality. Dysfunction of the autonomic nervous system is often combined with type 2 diabetes mellitus (T2DM) and cardiac autonomic neuropathy (CAN). The aim of the study was to analyze the peculiarities of short-term heart rate variability (HRV) in IDP with T2DM. Materials and methods. The study looked at three groups: 16 practically healthy individuals (group 1, controls), patients with T2DM and subclinical CAN (Lviv and region, group 2, n = 16) and IDP with T2DM and subclinical CAN (group 3, n = 16). No clinical symptoms of CAN were detected in the patients, and age, sex, duration of T2DM, body mass index, and HbA1c did not differ significantly (p > 0.05). Subclini­cal CAN was diagnosed according to the results of cardiovascular reflex tests and the Composite Assessment Symptom Score 31. The results of short-term HRV lasting 5 min were studied and analyzed. Results. A statistically significant rise in heart rate wase detected in patients with T2DM and subclinical CAN. At the same time, there was a significant decrease in the median RR interval (mRR); the percentage of adjacent NN intervals that deviate from one another by more than 50 ms (pNN50%); levels of the high frequency power (HF) and the high frequency normalized unit (HFnorm). In IDP with T2DM and subclinical CAN, compared to group 2, a further signifi­cant increase in heart rate was observed: 86.19 ± 82.30 [69.0; 121.0] bpm; a decrease in mRR: 709.56 ± 93.45 [496.0; 871.0] ms; the root mean square of successive differences between adjacent NN intervals: 17.56 ± 9.06 [5.0; 41.0] ms; pNN50%: 2.56 ± 4.66 [0; 17] %; low frequency power (LF): 626.56 ± 428.50 [156.0; 1358.0] ms2; HF: 143.81 ± 111.68 [10.0; 363.0] ms2; percentage of HF in the total HRV spectrum: 10.44 ± 8.15 [2.0; 26.0], as well as the growth of the LF normalized unit: 79.81 ± 14.25 [54.0; 96.0] n.u.; percentage of a very LF in the total spectrum: 47.50 ± 18.69 [12.0; 86.0] %. Conclusions. It was found that in IDP with T2DM and subclinical CAN, the total HRV power went down, and the sympathetic component became much stronger. This indicates the activation of the body’s adaptive reactions in response to stressful situations. The use of short-term HRV analysis can be both a cost-effective and scientifically sound approach for the early diagnosis of CAN in patients with T2DM. The data obtained can become the basis for the development of effective prevention strategies, as well as new methods of timely diagnosis and therapy of IDP with T2DM.