Aim To investigate the plasma apelin-12 level in the subjects with type 2 diabetes mellitus(T2DM)and its relationship with blood glucose. Methods 41 T2DM patients who were hospitalized in the department of endocrinology of civil aviation general hospital were selected from January 2012 to June 2015, and 44 healthy subjects were enrolled as control group. The patients with T2DM were divided into two groups including one group (21 persons) complicated with hypertension, cardiovascular and cerebrovascular disease and another group (20 persons) without complications for subgroup analysis. The level of apelin-12 was measured by enzyme linked immunosorbent assay. Glycosylated hemoglobin (HbA1c), cholesterol, triglyceride, low density lipoprotein, fasting blood glucose, 2-hour postprandial glucose (2hPG) and C peptide were determined in T2DM group and control group. The correlation between apelin-12 and clinical indicators was analyzed. Results (1) The content of apelin-12 was significantly lower in the T2DM group than in control group(t=2.70, P=0.01). (2)Subgroup analysis showed that there was no significant difference in plasma apelin-12 level between T2DM with cardiovascular and cerebrovascular diseases and T2DM without complications (t=－0.44, P=0.67). (3) With stepwise multiple regression analysis, taking apelin-12 as dependent variable, and age, body mass index, blood pressure, total cholesterol, triglyceride, low density lipoprotein, high density lipoprotein, HbA1c, fasting blood glucose, 2-hour postprandial blood glucose, fasting C-peptide and 2-hour postprandial C-peptide were independent variables, fasting blood glucose was associated with apelin-12 in T2DM patients(B=－0.12, β=－0.42, t=－2.03, P=0.04).Conclusion Plasma apelin-12 levels were significantly lower in patients with T2DM and were negatively correlated with fasting blood glucose.