Evidence suggests that in pregnant women who not meet criteria for Gestational diabetes mellitus (GDM) diagnosis, a cut-off value of 155 mg/dL at 1h during OGTT (1h-PG) is an independent predictor of impaired insulin sensitivity and beta-cell dysfunction. It is unclear whether 1h-PG in pregnant women with normal glucose tolerance (NGT-1h high) is associated with adverse pregnancy outcomes. To elucidate this issue, we evaluated maternal and neonatal outcomes in 215 pregnant women who underwent OGTT at 24-28 weeks for GDM screening. According to their glycemic levels, women were divided in 3 groups: NGT-1h high (n=31), NGT and PG<155 mg/dl (NGT-1h low) (n=130) and GDM (n=54). As compared with women NGT-1h low, those with GDM were older, and showed higher prevalence of history of GDM and higher fasting plasma glucose (FPG), 1h-PG and 2h-PG. In addition, women with GDM exhibited a significant higher age-adjusted cesarean delivery, newborns small (SGA) or large for gestational age (LGA) and neonatal hypoglycemia. Compared to women NGT-1h high, those with GDM showed higher FPG and 2h-PG levels. Interestingly, a significant greater proportion of women NGT-1h high exhibited an inappropriate weight gain as compared women with GDM, while no significant differences were observed in maternal and neonatal outcomes. Univariate correlations showed that 1h-PG was positively correlated with newborns SGA or LGA (r=0.310, p<0.001) and clinical neonatal hypoglycemia (r=0.156, p=0.03) and 2h-PG was positively correlated with newborns SGA or LGA (r=0.310, p<0.001). In a regression logistic model, as compared women NGT-1h low, both those NGT-1h high and GDM showed an increased risk of neonatal hypoglycemia (OR 2.19, 95%CI 1.004-3.39, p<0.0001, OR 1.81, 95%CI 1.01-2.61, p<0.0001, respectively). These data suggest that a cutoff point of 155 mg/dl for the 1-h PG during OGTT in pregnancy may be helpful in the identification of women with NGT at increased risk for adverse neonatal outcomes.