OBJECTIVE: The association between adiposity and heart rate variability (HRV) in patients with type 2 diabetes (T2D) after coronary artery bypass graft surgery (CABG) is not well documented. We evaluated the associations between indices of adiposity and HRV in patients with T2D with CABG and quantified the relationships of the volume of visceral (VVAT) and subcutaneous adipose tissue (VSAT) to HRV. DESIGN AND METHODS: One hundred and thirty-five men with T2D who underwent CABG participated in this study. HRV, BMI, waist circumference (WC), VVAT, and VSAT were measured. Correlations between indices of HRV and adiposity were evaluated and predictors of HRV modulation were identified. Patients were then divided into quartiles of VVAT and VSAT to further evaluate the influence of adiposity on HRV. RESULTS: Subjects were 65 +/- 7 years old (mean +/- SD) with a BMI of 30 +/- 4 kg/m(2) and a WC of 105 +/- 10 cm. BMI (r = -0.19) and WC (r = -0.25) were inversely correlated with low frequencies. VVAT correlated negatively with SD normal-to normal (SDNN) (r = -0.22, P < 0.01), indices of cardiac parasympathetic activity [rMSSD (r = -0.27), NN50 (r = -0.22), pNN50 (r = -0.26; all P < 0.05], and with low (r = -0.37) and high frequencies (r = -0.20; all P < 0.01). Patients with the lowest VVAT had the highest cardiac parasympathetic activity (P < 0.05). VVAT remained the best predictor of cardiac parasympathetic activity after adjustments for confounding parameters (P < 0.01). CONCLUSION: An increase in visceral adiposity, not BMI, seems to be associated with lower HRV in patients with T2D who had a CABG procedure.