Objective:To study the correlation between midpregnancy adiponectin level and gestational diabetes mellitus(GDM). Methods:75 g oral glucose tolerance tests were performed in 305 pregnant women at 24 to 28 weeks of gestation. Fasting maternal blood samples were drawn to determine plasma concentrations of adiponectin,glucose,insulin,free fatty acid,and blood lipids. Blood samples at 1 and 2 h after an oral glucose load were obtained to measure plasma glucose and insulin concentrations. Results:Plasma adiponectin concentrations were significantly lower in women who had GDM than in those who had normal glucose tolerace(NGT)(P = 0.014). The multiple logistic regression model showed that the association between BMI before pregnancy and GDM remained significance(P = 0.017) after adjusting for plasma adiponectin and FFA concentrations. The obese women had significantly lower midpregnancy adiponectin concentrations than non-obese women. In the NGT group,maternal adiponectin concentrations were significantly negatively correlated with plasma fasting insulin,1-h glucose,triacylglycerol and maternal BMI(at blood collection and at delivery),and positively correlated with high-density lipoprotein cholesterol and total cholesterol concentrations.In the GDM group,maternal adiponectin level was negatively correlated with neonatal birth weight and low-density lipoprotein cholesterol concentrations. Conclusion:Midpregnancy lower adiponectin level might be associated with a higher risk of GDM.