Objective To study the change of diastolic cardiac function in diabetic patients and to determine the diagnostic value of plasma brain natriuretic peptide (BNP) and atria natriuretic peptide (ANP) for diastolic heart failure in patients with type 2 diabetes mellitus. Methods Twelve healthy subjects and seventy-one diabetic patients were included in the study. Plasma BNP and ANP were measured with immunoradiometic assay. Results Plasma levels of BNP and ANP increased significantly with increased severity of diastolic heart dysfunction. The ratio of E/A had significant negative correlation with the plasma levels of BNP (r=-0.669,P<0.001) and ANP (r=-0.579, P<0.01). AUC of ANP and BNP in ROC model was 91.9% and 65.3%, respectively. Conclusions The plasma level of BNP might be a valuable predictor for differential diagnosis of diastolic cardiac function in diabetic patients.