Aim To explore the diagnostic value of plasma NT-proBNP level on short-term prognostic outcomes in patients with acute coronary syndrome （ACS） and type 2 diabetes mellitus （T2DM）. Methods The follow-up data of 248 in-patients with ACS and T2DM were collected to study. All patients were divided into four groups （Q1-Q4） according to the quartile of the NT-proBNP levels. The global registry of acute coronary events （GRACE） scores and the occurrence of major adverse cardiac events （MACE） were compared among four groups. With 6 months of follow-up, all patients were divided into two groups, control group （116 cases, non-compliance with MACE） and research group （132 cases, compliance with MACE）, according to the prognostic outcome. The indexes of NT-proBNP, HbA1c, FBG, PBG and the GRACE score were compared between two groups. The correlations of the above factors and HR, SBP, Killip class, coronary blood flow TIMI grade to the occurrence of MACE were confirmed by Logistic regression analysis. The best cutoff point of NT-proBNP was confirmed by the areas under the receiver operating curve （ROC）. Results The sequence of the GRACE score and high-risk percent to Q1-Q4 groups was Q4>Q3>Q2>Q1 （P<0.05）, and the sequence of the MACE occurrence was also Q4>Q3>Q2>Q1 （P<0.05）. After follow-up for 6 months, compared to control group, the value of NT-proBNP and GRACE of research group were higher （P<0.05）, but the values of HbA1c, FBS and PBS were not different （P>0.05）.