CDKAL1 and gestational diabetes: Using an age-matched case-control study nested in a large population-based cohort of pregnant women in Tianjin, China, this analysis aimed to explore 1) additive interactions between CDKAL1 rs7747752 polymorphism and low GUDCA/DCA for the risk of GDM; and 2) whether the additive interactive effect if any between rs7747752 polymorphism and low GUDCA/DCA on the risk of GDM was mediated via LPC18:0 and/or SFA16:0.