Effects of 12 Weeks Practice of Yoga on Heart Rate Variability in Males with Type 2 Diabetes Receiving Oral Antidiabetic Drugs: A Randomized Control Trial

Objective: To investigate the effects of 12 weeks practice of a structured yoga module on heart rate variability (HRV) and cardiometabolic risks in patients with type 2 diabetes (T2D) receiving similar kind of oral antidiabetic drugs (OAD) with yoga therapy and without yoga therapy, matched for all the known confounders. Design: Parallel design interventional (randomized control trial) study. Subjects: Eighty treatment-naive males with T2D were randomized into control group (n = 40) and study group (n = 40). Intervention: Study group participants received a structured yoga therapy that included asana and pranayama practice for 12 weeks in addition to OAD, whereas control group participants received OAD alone. Outcome measures: Before and after intervention, BP parameters, rate pressure product (RPP) as the marker of myocardial stress, total power (TP) of HRV, low-frequency to high-frequency (LF-HF) ratio of HRV, homeostatic model of insulin resistance (HOMA-IR), lipid profile and lipid risk factors, malondialdehyde (MDA), and high-sensitive C-reactive protein (hsCRP) were measured. TP of HRV was defined as the primary outcome. Association of TP (the marker of HRV) and LF-HF ratio (the marker of sympathovagal balance) with cardiometabolic parameters was assessed by correlation and regression analyses. Results: After 12 weeks yoga therapy, there was significant reduction in cardiometabolic risks (TP of HRV, RPP, lipid risks factors, levels of MDA, and hsCRP) in study group subjects compared with control subjects that did not receive yoga therapy. All cardiometabolic risk factors were significantly correlated with TP in study group, having maximum significance with homeostatic model of insulin secretion (r = 0.502, p ≤ 0.001). Multiple regression analysis demonstrated the independent contribution of decrease in RPP, HOMA-IR, hsCRP, and MDA to increased TP and decreased LF-HF ratio in T2D patients after yoga therapy. Conclusion: From the results of this study, the authors conclude that 12 weeks practice of a structured yoga module improves TP of HRV, sympathovagal balance, and metabolic functions, and reduce cardiovascular (CV) risks in patients with diabetes who received routine antidiabetic medicines along with yoga therapy, compared with the patients with diabetes who received antidiabetic medicines alone. The reduction in cardiometabolic risks in these patients is linked to the improvement in TP of HRV. Future studies should also include a control group with rapid walking or a similar exercise program of equal time to the yoga intervention group to discern whether it is in fact yoga that is leading to these results and not simply increased CV activity. Clinical Trial Registry of India (No. CTRI/2021/06/034074).

Keywords: cardiometabolic risks; heart rate variability; rate pressure product; sympathovagal imbalance; type 2 diabetes mellitus; yoga.

PMID: 34582701 DOI: 10.1089/acm.2020.0489