GDM cases (N = 173) and controls (N = 187) were selected from among participants of a cohort study of risk factors of pregnancy complications. Early pregnancy (16 weeks on average) serum RBP4 concentration was measured using an ELISA-based immunoassay. Logistic regression was used to estimate unadjusted and adjusted odds ratios (ORs/aORs) and 95 % confidence intervals (95 % CI).
Mean serum RBP4 was significantly higher among GDM cases compared with controls (47.1 vs. 41.1 ¦Ìg/ml, respectively; p-value <0.05). Participants in the highest quartile for serum RBP4 had a 1.89-fold higher risk of GDM compared with participants in the lowest quartile (95 % CI: 1.05-3.43). However, this relationship did not reach statistical significance after adjustment for confounders (aOR: 1.54; 95 % CI: 0.82-2.90). Women who were ¡Ý35 years old and who had high RBP4 (¡Ý38.3 ¦Ìg/ml, the median) had a 2.31-fold higher risk of GDM compared with women who were <35 years old and had low RBP4 (<38.3 ¦Ìg/ml) (aOR: 2.31; 95 % CI: 1.26-4.23; p-value for interaction = 0.021).
Overall, there is modest evidence of a positive association of early pregnancy elevated RBP4 concentration with increased GDM risk, particularly among women with advanced age.