Objectives: Diabetes mellitus is an independent and strong risk factor for development of atrial fibrillation (AF). Electrophysiologic and electromechanical abnormalities are associated with a higher risk of AF. In this study we aimed to determine the correlation of atrial conduction abnormalities between the surface electrocardiographic and tissue Doppler echocardiographic measurements in type 2 diabetes mellitus (T2DM) patients. Methods: A total of 88 consecutive T2DM patients and 49 age-, gender-, and body mass index-matched healthy volunteers were included in the present study. Baseline characteristics were recorded and 24-hour ambulatory blood pressure monitoring, transthoracic echocardiography, and 12-lead surface electrocardiography were performed for all study participants. Atrial electromechanical delay (EMD) intervals were measured. Results: Maximum P-wave duration and P-wave dispersion (Pd) were significantly higher in patients with T2DM (105.7 ± 10.2 ms vs. 102.2 ± 7.5 ms, p = 0.02; 40.6 ± 7.6 ms vs. 33.6 ± 5.9 ms, p < 0.001, respectively). Interatrial, intraatrial, and intraleft atrial EMD were significantly higher in the T2DM patients when compared with the controls (16.5 ± 7.8 ms vs.11.2 ± 4.4 ms, p < 0.001; 9.0 ± 7.3 ms vs. 6.0 ± 3.8 ms, p = 0.002, and 7.4 ± 5.2 ms vs. 5.1 ± 3.2 ms, p = 0.002 respectively). Correlation analysis showed a positive correlation between interatrial EMD and Pd (r = 0.429, p < 0.001) and left atrial volume (r = 0.428, p < 0.001). Conclusions: In this study, there was significant EMD and Pd in patients with T2DM as compared with healthy volunteers. Additionally, interatrial EMD was correlated with Pd and left atrial volume index.