Prediction of cardiac autonomic dysfunction using heart rate response to deep breathing test among type 2 diabetes mellitus

Background: Cardiac autonomic neuropathy (CAN) is an underdiagnosed complication of type 2 diabetes mellitus (T2DM) and a predictor of mortality and cardiovascular morbidity. Hence, CAN screening is essential. The objective of the study was to examine whether cardiac autonomic dysfunction can be predicted using the heart rate response to deep breathing test of cardiac autonomic reflex tests (CARTs) among type 2 diabetes mellitus. Methods: The study was a cross-sectional study of T2DM individuals between 40 and 65 years. Each participant underwent a heart rate (HR) response to deep breathing test (CARTs) as per standard guidelines. ANOVA F-test was used to check the difference between the CAN severity and the heart rate response to deep breathing parameters. A post-hoc (Tukey’s) test was used to check which groups showed the difference. Results: Eighty-four participants were screened, of which forty-one were included in the present study. The mean age of the participants was 58.8 ± 4.0 years. The Fisher’s test showed a statistically significant difference between groups for the average deep breathing difference (F(3,27) = 16.09, p < 0.001) and the respiratory sinus arrhythmia index (F(3,27) = 7.35, p < 0.001). Conclusion: HR response to deep breathing can be used as a preliminary tool to screen CAN in T2DM to differentiate between normal and the other stages of CAN, which can then be followed by the gold standard tests. Further studies are required to establish HR response to deep breathing as a singular tool using regression analysis. Clinical Trials Registration: The study was registered prospectively in the Clinical Trials Registry- India (CTRI/2023/11/060077) on 21st November 2023.