Effect of supine rest on cardiac autonomic tone in type 2 diabetes mellitus

Background: Autonomic nerve dysfunction has been noted in type 2 diabetes mellitus (T2DM). Regular practice of supine rest (SR) may cause improvement of this impaired autonomic nerve function. Objective: To observe the effect of SR on the autonomic nerve activity by analysis of heart rate variability (HRV) in patients with T2DM. Methods: This prospective interventional study was carried out in the Department of Physiology, Bangabandhu Sheikh Mujib Medical University (BSMMU)during 2016 on 30 female diagnosed T2DM patients aged 50-55 years with duration of diabetes of 5-10 years. They performed SR (20 minutes twice daily) for 3 months. The diagnosed patients were selected from the Out Patient Department of Endocrinology, BSMMU, Dhaka. Thirty age matched apparently healthy females who did not perform regular SR, were control. To assess the cardiac autonomic nerve function, HRV parameters of all subjects were recorded by PowerLab. HRV data of all subjects were collected at baseline and also after 3 months follow-up. In addition, urinary level of Vanillyl Mandelic acid (VMA) of all subjects were measured at baseline and at post intervention period for patients. For statistical analysis, paired and independent sample t-tests were done, as applicable. Results: The pre-intervention values of LF normalized unit (LF nu), LF/HF ratio(p<0.01) and urinary VMA were significantly higher(p <0.001) and HF normalized unit (HF nu) was significantly (p<0.01)lower in all diabetic patients compared to control. The post-intervention data showed LF nu, LF/HF ratio and urinary VMA were reduced and HF nu was increased but these changes were not statistically significant (p> 0.05) in diabetic patients. Conclusion: This study concluded that parasympathetic activity decreased, increased sympathetic activity with higher sympathovagal balance indicating autonomic dysfunction in patients with T2DM, which was shown with trend of improvement after regular practice of supine rest of 3 months though statistically not significant. Bangladesh Soc Physiol. 2017, December; 12(2): 65-71