Abstract：Objective To investigate the clinical value of tissue Doppler imaging  in assessing left ventricular diastolic function and filling pressures in patients with diabetic mellitus. Methods A total of 101 patients with diabetes mellitus treated in Dongguan Hengli Hospital from October 2023 to March 2025 were retrospectively included as group A, while 48 non-diabetic subjects were selected as group B. All participants underwent conventional echocardiography and tissue Doppler imaging. Conventional parameters, including the peak early diastolic velocity （Peak E） and late diastolic velocity （Peak A） of mitral inflow, were compared between the two groups, along with tissue Doppler imaging parameters: early （E’） and late （A’） diastolic peak velocities at the septal mitral annulus, early （Em） and late （Am） diastolic velocities at the lateral annulus, the E’/A’ ratio, annular E/E’, lateral E/Em, and the average E/e’ ratio.  Results Compared with group B, patients in group A showed significantly higher values of Peak A, A’, Am, annular E/e’, lateral E/Em, and average E/e’, and significantly lower values of Peak E, E’, Em, and E’/A’. The differences between the two groups were statistically significant （t＝6.951, 5.484, 4.723, 8.514, 7.642, 8.489, 3.340, 22.205, 19.940, 23.512; all P＜0.05）. Conclusion Tissue Doppler imaging can effectively assess left ventricular filling pressure and diastolic dysfunction in patients with diabetes mellitus. Compared with conventional echocardiography, tissue Doppler imaging demonstrates better feasibility and reproducibility, enabling earlier detection of diastolic dysfunction and providing a reliable diagnostic basis for clinical evaluation and management.