Correlates of SDNN heart rate variability in healthy subjects and subjects with type 2 diabetes mellitus

Introduction :Standard deviation of R-R intervals (SDNN) predicts mortality in variety of clinical conditions. But little is known about correlates of SDNN. Objective: To investigate correlates of SDNN in healthy subjects andwith type 2 diabetes. Materials and Methods :115 male subjects with type 2 diabetes and 87 controls were studied. In them heart rate (HR), blood pressure (BP), body mass index (BMI), Q -Tc and SDNN were measured. Pearson correlation coefficient and unpaired t test were used for data analysis. P 0.05 was considered significant. Results : In controls, SDNN was negatively correlating with age and HR (p 0.05, 0.001 respectively). In subjects with type 2 diabetes, SDNN was negatively correlating with HR, diastolic blood pressure and Q-Tc (p 0.0001, 0.01, = 0.014 respectively); and was positively correlating with BMI (p 0.05). Conclusion : Higher HR, DBP and prolonged Q-T interval are associated with reduced SDNN in subjects with type 2 diabetes. In them BMI could be a confounding factor while assessing cardiac autonomic dysfunction employing SDNN. In healthy subjects high HR and age is associated with reduced SDNN.