The aim of this study was to compare pregnant women with and without gestational diabetes (GDM) with regard to third trimester adiponectin, leptin and insulin resistance, as well as to investigate their relation to fetal growth and macrosomia. 134 pregnant women were enrolled in the study: 86 with GDM and 48 controls. Maternal plasma adiponectin, leptin, fasting insulin, glucose and fetal biometry were measured between 27 and 32 weeks of gestation. Birthweight and delivery data were also assessed. Adiponectin in GDM patients was lower when compared to non-diabetic women while mean leptin concentration was not different. In GDM group only mothers' weight gain until third trimester was significantly different between the groups of patients with normal and accelerated fetal growth. No correlation of adiponectin and leptin with fetal growth was shown. Mothers' weight gain until third trimester and mean fasting glucose between 33 and 34 weeks of gestation were associated with neonatal macrosomia. There were no differences in adiponectin and leptin between mothers of macrosomic and non-macrosomic neonates. Fetal growth seems not to be related to third trimester adiponectin and leptin concentrations, while increased third trimester fasting glucose may be an independent risk factor of macrosomia.