Abstract: Objective To study insulin resistance and beta-cell function of Shenyang subjects with impaired glucose tolerance (IGT) and to investigate the pathogenesis of type 2 diabetes mellitus (T2DM). Methods We performed the study in a total of 34 subjects with varying degree of glucose tolerance (12 subjects with normal glucose tolerance (NGT), 14 with IGT, and 8 with DM). Insulin resistance was measured using hyperinsulin-euglycemic clamp, and beta-cell function was assessed by intraveneous glucose tolerance test. Results Compared with the NGT group, the subjects with IGT had significantly lower glucose infusion rate (GIR, mg·kg-1·min-1) (5.1±0.6 vs 10.1±1.0, P<0.01), significantly increased fasting plasma insulin level (28.1±3.4 vs 12.6±1.1 mU/L, P<0.01), markedly reduced first-phase insulin secretion (11.3±2.9 vs 43.0±9.6 mU/L, P<0.01) and markedly elevated second-phase insulin secretion (35.3±7.3 vs 15.3±2.0 mU/L,P<0.01). The GIR in the subjects with DM was as great as that in those with IGT (4.5±0.4 vs 5.1±0.6, P=0.53 ), but fasting plasma insulin level in the DM group was significantly lower than that in the IGT group(13.9±1.1 vs 28.1±3.4 mU/L, P<0.01). Conclusion Both insulin resistance and insulin secretion dysfunction are associated with the transition from NGT to IGT in Chinese northeast (subjects.)