Supplementary Material for: A Prospective Study of Maternal Plasma Concentrations of Retinol-Binding Protein 4 and Risk of Gestational Diabetes Mellitus

Background: The aim of this study was to investigate whether retinol-binding protein 4 (RBP4) concentrations, measured at the first prenatal visit, are associated with risk of gestational diabetes mellitus (GDM). Methods: From July 2015 to June 2016, consecutive women who admitted to the obstetrics center of our hospital were included. At the first prenatal visit (the median gestational age was 6 [interquartile range 4–10] weeks) in the hospital, involved subjects were tested for fasting plasma glucose (FPG) and RBP4 using venous plasma samples collected after at least 8 h of fasting in the morning. Data for FPG and RBP4 concentrations at the first prenatal visit and one-step GDM screening with 75-g oral glucose tolerance test performed between 24 and 28 weeks of gestation were collected and analyzed. Results: Blood at first prenatal visit was available for 827 women, among whom GDM developed in 101 (12.2%). In multivariate models comparing the second (Q2), third, and fourth quartiles against the first quartile of RBP4, concentrations of RBP4 in Q2, Q3, and Q4 were associated with GDM later developed, and increased risk of GDM by 54, 205, and 536%. There was a significant statistical difference in the area under the curve between the established risk factors alone and the addition of RBP4 concentrations (difference, 0.039 [95% CI 0.030–0.052]; p = 0.03). In the subgroup of women combined with obesity and FABP4 ≥median, the measured OR was 9.83 (95% CI [4.76–16.13]; p < 0.001) for GDM compared to those without obesity and FABP4 Conclusions: There is evidence of a positive association of early pregnancy elevated RBP4 concentration with increased GDM risk, particularly among women with advanced age and obesity.