Neutrophil gelatinase-associated lipocalin (NGAL) is highly expressed in damaged epithelia, during inflammation and cardiovascular disease. Soluble NGAL was measured in women who subsequently developed gestational diabetes.From a cohort of 908 pregnant outpatients who participated in a screening programme for Down's syndrome at 9-12 weeks of gestation, we considered all 41 women with a singleton pregnancy, who developed gestational diabetes in the previous 12 months, and a control group of 82 normal pregnancies. Circulating NGAL and insulin resistance by homeostasis model assessment ratio (HOMA-IR) were determined in the first trimester.Median serum NGAL concentrations were higher in the gestational diabetes group [51.3 ng/ml (39.8-66.1 ng/ml)] compared with the control group [17.8 ng/ml (15.5-20.9 ng/ml)] (P0.001) and positively correlated with HOMA-IR (P0.001).In the first trimester, circulating NGAL was significantly increased in women who subsequently developed gestational diabetes compared with the control group.