Objective  To analyze the changes of heart rate variability (HRV) in type 2 diabetes mellitus (T2DM) patients complicating with coronary heart disease (CHD), and its correlation with cardiac function.

  Methods  Totally 58 patients with T2DM but without CHD (T2DM group), 40 patients with T2DM and CHD (T2DM with CHD group), and 30 healthy volunteers (control group) were selected as research subjects. The correlations of HRV parameters24 h standard deviation of normal R-R intervals (SDNN), root mean sum of the squared differences between R-R intervals (rMSSD), percetange of adjacent NN intervals differing by more than 50 ms (PNN50), very low frequency (VLF), low frequency (LF), high frequency (HF)with the grade of cardiac function and the severity of coronary artery lesions were analyzed.

  Results  The SDNN, rMSSD, PNN50, VLF, LF and HF were lower in the T2DM group and the T2DM with CHD group than those in the control group, and lower in the T2DM with CHD group than those of the T2DM group (P < 0.05). With the increase of New York Heart Association (NYHA) grade and the number of coronary artery lesions, SDNN, rMSSD, PNN50 and HF decreased, with statistically significant differences (P < 0.05). SDNN, rMSSD, PNN50 and HF were negatively correlated with NYHA grade in the T2DM with CHD group (P < 0.05). The rMSSD, PNN50 and HF were negatively correlated with the severity of coronary artery lesions (P < 0.05).

  Conclusion  HRV parameters show a decreasing trend in patients with T2DM and CHD. SDNN, rMSSD, PNN50 and HF are related to cardiac function, while rMSSD, PNN50 and HF are related to the severity of coronary artery lesions.