Objective：To explore influence of viable myocardium in myocardial infract region on left ventricular remodeling and left cardiac function in diabetic patients with acute myocardial infarction (AMI) after percutaneous coronary intervention (PCI). Method: A total of 208 patients with type 2 diabetes mellitus (T2DM) complicated AMI after PCI underwent myocardial metabolic imaging by 18F- deoxyglucose position emission tomography (18F-FDG PET) and myocardial perfusion imaging by 99mTc-methoxy isobutyl isonitrile single photon emission computed tomography (99mTc-MIBI SPECT). According to whether there was viable myocardium in myocardial infarct region, patients were divided into viable myocardium group (n=115，perfusion didn’t match metabolism) and no viable myocardium group (n=93, perfusion matched metabolism). Indexes of echocardiography were measured in two groups before and after PCI. Influence of viable myocardium in myocardial infarct region on left ventricular remodeling and cardiac function was observed. Result: After myocardial infarction 12 months, compared with no viable myocardium group, there was significant increase in left ventricular ejection fraction (LVEF) [(44.1±7.12)% vs. (46.7±6.98)%] and significant decrease in left ventricular end-diastolic dimension (LVEDd) [ (55.46±4.75) mm vs. (53.17±4.77) mm], left atrial diameter [ (39.25±11.31) mm vs. (35.89±12.08) mm] in viable myocardium group, P＜0.05 all. There were no significant difference in ratio of mitral diastolic peak flow velocity (E/A) in two groups after 12 months (P＞0.05). Conclusion: In patients with type 2 diabetes mellitus complicated acute myocardial infarction, compared with no viable myocardium patients, LVEF significantly improves, LVEDd significantly decreases in patients with viable myocardium within myocardial infract region.