To evaluate the value of left ventricular diastolic function in type 2 diabetes mellitus (DM) using dual-gate Doppler and relative factors, we included 50 non-obesity and hypertension-free DM patients into the controlled group in the study along with 48 age-and-gender-matched healthy volunteer subjects. The peak early diastolic velocity (E), peak later diastolic velocity (A), deceleration time (DT), anterior mitral annulus diastolic peak velocity (e'), isovolumic relaxation time (IVRT), E/A, E/e', Tei index and TE-e' were measured with dual-gate Doppler. 20 subjects were randomly selected for repetitive analysis. Study showed statistical difference in E/A, DT, e', E/e', IVRT, Tei index and TE-e' between the two groups (P < 0.05). Linear regression analysis showed positive correlation between TE-e' and IVRT, course of DM patients and TE-e'(Beta=0.295, P=0.020), and HbA1C control level and TE-e'(Beta=0.399, P=0.010). Repeated analysis showed good reproducibility for both within and between groups. Dual-gate Doppler has clinical value in evaluating left ventricular diastolic function in type 2 diabetes mellitus patients. The course of type 2 diabetes mellitus patients and HbA1C control level were both closely related with left ventricular diastolic function.