Objective To quantitatively evaluate the early changes of of the left ventricle(LV) in patient with type-2 diabetes mellitus（T2DM）by three-dimensional speckle-tracking imaging(3DSTI) Methods 50 T2DM patients (DMA group) with normal left ventricular systolic function (LVEF≥50％%), 30 T2DM patients (DMB group) with reduced left ventricular systolic function (LVEF < 50%) and 42 healthy volunteers (NC group) were selected. The peak longitudinal strain rate (GLS), radial strain rate (GRS), circumferential strain rate (GCS) and area strain rate (GAS) of left ventricle were measured by three-dimensional speckle tracking technique.. Results C Compared with NC group, DMA GLS, GCS and GAS decreased significantly, while GRS increased significantly (P < 0.05). GLS, GCS and GAS in DMB group were significantly decreased (P < 0.05), while GRS had no difference (P > 0.05). In addition, GLS, GCS, GRS and GAS in DMB group were significantly lower than those in DMA group (P < 0.05) Conclusio 3D-STI can be used to detect early left ventricular systolic dysfunction in T2DM patients, and is a reliable method to evaluate early myocardial lesions in diabetic patients.