Objective Obesity, older age, previous gestational diabetes mellitus (GDM), and family history of diabetes are risk factors but poor predictors of GDM. Therefore, we evaluated whether secretion patterns of adipokines or gestational hormones might be linked to risk for GDM among Korean women. Methods Non-GDM and GDM participants were divided into normal and overweight groups according to prepregnancy BMI above or below 23 kg/m2 at 24-28 weeks of pregnancy. Glucose tolerance, insulin resistance and secretory capacity, anthropometric and dietary data, and serum levels of adipokines and gestational hormones were determined. Results GDM was associated mainly with increased insulin resistance in overweight women and decreased insulin secretory capacity in normal weight women. Serum adiponectin and resistin levels were lower in GDM women than non-GDM women. In addition, serum visfatin was markedly decreased in both overweight and normal weight GDM women. Serum C-reactive protein levels were higher in overweight GDM subjects than overweight non-GDM women while serum progesterone was greater in GDM women than non-GDM women. These differences were involved in higher energy and saturated fat intakes in both normal weight and overweight GDM women than non-GDM women. Conclusion GDM in normal-weight Korean women is primarily due to poor insulin secretory capacity, but in overweight GDM women it was primarily due to insulin resistance. Low visfatin levels appear to be a common risk factor for both types of GDM. More research is needed to confirm that low levels of visfatin are involved in the etiology of GDM.