Three-dimensional speckle tracking echocardiography (3D-STE) was used to evaluate the improvement of continuous subcutaneous insulin infusion on the left ventricular (LV) systolic function of patients with type 2 diabetes mellitu (T2DM). We recruited T2DM patients (38 cases, diabetic group) and healthy volunteers (35 cases, control group) to collect LV full volume imaging. TomTec software was used for calculating LV global longitudinal strain (LVGLS), global circumferential strain (LVGCS), peak twist (LVTW), peak apical rotation (LVPAR), ejection fraction (LVEF), and torsion (LVT). All indices were re-tested 2 weeks later after intensive treatment of insulin pump. LVGLS, LVGCS, LVTW and LVPAR in diabetic group were significantly decreased than control group. LVGLS and LVGCS in pre-treatment diabetic group were significantly increased than post-treatment. LVGLS, LVGCS, LVTW and LVPAR had correlations among control, pre-treatment and post-treatment diabetic groups. There were no significant differences in LVEDV, LVESV, LVEF, LVT and R-R. LV systolic function of patients with T2DM complicated with microangiopathy was improved after treatment of continuous subcutaneous insulin infusion. In addition, therapeutic effect could be accurately evaluated by 3D-STE which had vital clinical application.