Abstract: Objective To study the changes of serum neuropeptide Y (NPY) and its correlation with left heart morphology and function in patients with type 2 diabetes at different blood pressure levels. Methods One hundred and sixty five type 2 diabetes patients, including 40 type 2 diabetes patients (DM group) and 125 type 2 diabetes patients with hypertension (DH1 group, n=40; DH2 group, n=41; DH3 group, n=44), 35 healthy people as NS group were enrolled in this study. The serum NPY level was detected by ELISA. Echocardiographic parameters including interventricular septal thickness (IVST), left ventricular end-diastolic diameter(LVEDD), left ventricular posterior wall thickness (LVPWT), left atrial diameter (LAD), and left ventricular ejection fraction(LVEF) were measured, then left ventricular mass index (LVMI) and E/A were calculated. The differences in all the indicators were compared between each group. Results There were significant differences in echocardiographic parameters between NS group and diabetes groups (DM group, DH1group, DH2 group and DH3 group) (all P< 0.05). With increasing of hypertension grade, the levels of IVST, LVEDD, LVPWT, LAD, lLVMI and NPY in DM, DH1, DH2 and DH3 groups increased, and LVEF, E/A decreased gradually. However, among DH groups, only the differences between DH3 group and other 2 groups were significant.Echocardiographic parameters in DH3 group, DH2 group and DH1 group were as follows, IVST (11.71±0.82 mm vs 10.66±1.06 mm, 9.89±0.93 mm); LVEDD (49.36±2.14 mm vs 44.67±2.99 mm, 41.86±2.89 mm); LVPWT (10.02±0.85 mm vs 8.86±0.85 mm, 6.9±0.92 mm); LVMI (136.96±11.17 g/m² vs 70.68±14.35 g/m², 64.10±8.46 g/m²); NPY: (15.53±4.35ng/L vs 10.56±3.64 ng/L, 8.67±3.52 ng/L), LVEF (60.97%±6.70% vs 67.62%±3.24%, 70.71%±5.17%) and E/A (0.50±0.09 vs 1.07±0.32, 1.33±0.45) (all P< 0.05). LAD in DH2 group and DH3 group were 31.06±2.55 mm and 29.91±1.82 mm, which were significantly lower than that in DH1 group (36.10±3.02 mm) (P< 0.05). Further multiple regression analysis showed that LVMI was independently correlated with the level of NPY (r=0.57, P=0.000). Conclusion With the rising of blood pressure, the left ventricular systolic function decreases, while left ventricular hypertrophy progresses, so does the levels of serum NPY. NPY may play an important role in the changes of left heart morphology and function in diabetes patients with hypertension.