Objective: The objective of this study is to investigate the urinary neutrophil gelatinase-associated lipocalin (uNGAL) levels in the second trimester of pregnant patients at the time of gestational diabetes mellitus (GDM) screening.Materials and methods: Urinary samples from 88 pregnant women who underwent gestational diabetes screening test were collected in late second trimester (24-28 weeks) prospectively. After an overnight fasting, 75g GTT was performed. The blood samples were drawn for measurement of glucose, insulin, and HbA1c. The urinary and blood parameters were compared for pregnant women with or without gestational diabetes.Results: uNGAL levels were significantly elevated in pregnant women with gesting compared with the control groups (p<.014). There was a positive correlation between uNGAL and HbA1c levels (p=.001).Conclusions: In the second trimester, at the time of GDM screening, high levels of uNGAL indicate tubular injury in GDM cases which seems to be a result of hyperglycemia. uNGAL may correlate with an inflammatory renal involvement in GDM.