D’Souza, LeroyChikkaiah, Prakash BanahalliK. S., PrashanthSinghvi, Maanini2026-06-052026-06-052026-03European Journal of Clinical and Experimental Medicine T. 24, z. 1 (2026), s. 96–1032544-1361https://repozytorium.ur.edu.pl/handle/item/12510The study was conducted in accordance with the Declaration of Helsinki, and the protocol was approved on 16/6/2023 by the BMCRI Institutional Ethics Committee, Bangalore Medical College and Research Institute, Bangalore (No: BMCRI/PS/85/2022-23).Introduction and Aim. Irritable bowel syndrome (IBS) and functional dyspepsia (FD) are functional gastrointestinal disorders that may involve autonomic imbalance. This study assessed autonomic nervous system activity using short-term heart rate variability (HRV). To our knowledge, this is the first study in an Indian population to directly compare autonomic modulation across IBS subtypes and FD using a unified HRV protocol, demonstrating subtype-specific alterations ‒ particularly reduced LF/HF in IBS-diarrhea (IBS-D). Material and methods. Thirty IBS patients and thirty FD patients diagnosed using the Rome IV criteria, along with thirty healthy controls, were enrolled. Short-term HRV analysis was performed following ECG acquisition using the LABCHART platform. Results. Mean low-frequency/high-frequency (LF/HF) ratio was 1.26±0.83 in IBS, 1.40±1.171 in FD, and 1.60±1.196 in controls. High-frequency (HF) power values (ms²) were 733.9±1661.16 (IBS), 534.18±778.28 (FD), and 674.87±1187.16 (controls), with no significant differences among the three groups (p>0.05). Subgroup analysis revealed significantly lower LF/HF values in IBS-D compared to controls (0.98±0.69 vs. 1.60±1.196; p=0.038), while HF values did not differ (p>0.05). No significant differences were found between IBS-constipation (IBS-C) patients and controls. Conclusion. IBS-D patients exhibited decreased LF/HF and increased HF values, indicating enhanced parasympathetic modulation, which may contribute to diarrhea-predominant symptoms. IBS-C patients showed a trend toward higher LF/HF and lower HF values, compatible with increased sympathetic modulation, although results were not statistically significant. FD patients showed no autonomic differences relative to controls. These findings highlight subtype-specific autonomic patterns in IBS and provide novel HRV-based insights from an Indian cohort.engAttribution-NonCommercial-NoDerivatives 4.0 Internationalhttp://creativecommons.org/licenses/by-nc-nd/4.0/autonomic imbalanceautonomic nervous systemconstipationdyspepsiagastrointestinal diseasesirritable bowel syndromearticle10.15584/ejcem.2026.1.17