Objective To explore the value of speckle tracking echocardiography (STE) with low dose dobutamine stress echocardiography (LDDSE) for evaluation of viable myocardium (VM) in the acute ST-elevation myocardial infarction (STEMI) patients with or without type 2 diabetes mellitus (DM). Methods Eighty-five hospitalized patients with regional wall motion abnormalities (RWMA) according to routine echocardiography in STEMI, thirty patients with type 2 DM. All of them were underwent STE associated with LDDSE (STE-LDDSE) prior to coronary angiography and percutaneous coronary intervention (PCI). Every segment image was acquired and evaluated by wall-motion analysis. The images of STE-LDDSE were analyzed quantitatively for peak-systolic strain (S) and strain rate (Sr), the short axis of radial strain (RS), radial strain rate (RSr), circumferential strain (CS), circumferential strain rate (CSr) and the long axis of longitudinal strain (LS), longitudinal strain rate (LSr) by using the QLAB software. All patients underwent PCI within one week after completing STE-LDDSE examination, and echocardiograms were reviewed at 1, 3, and 6 months after surgery. Results A total of 183 regional wall motion abnormalities (RWMA) were detected in the DM group, of which 117 (63.93%) segments were viable myocardium; 357 RWMA were detected in non DM patients, of which 248 (69.47%) segments of viable myocardium were detected by echocardiography. The sensitivity, accuracy, and specificity of STE-LDDSE in detecting viable myocardium in DM group were 70.94%、77.45%、87.88% ; 92.31%、72.73% and 85.25% for LS and LSr. In the non DM group, the sensitivity, specificity, and accuracy of LS and LSr were 68.95%、92.66%、76.19% ; 77.42%、88.07% and 80.67%, respectively. Further parallel diagnostic tests were conducted on LS and LSr parameters. The sensitivity, specificity, and accuracy of detecting viable myocardium in the DM and non DM groups were 84.62%、45.45%、70.49%, 66.53%、63.30% and 65.55%, respectively, at rest; They were 84.62%、45.45%、70.49%, 66.53%、63.30% and 65.55%, respectively, during low dose dobutamine stress. Conclusion STE-LDDSE has a high value of detecting VM. Parallel diagnostic test for LS and LSr is the best choice in detecting VM in the patients with STEMI and is more sensitive for the patients with type 2 DM. It will be more effectively to guide the further treatment and to evaluate the prognosis of the STEMI patients.