Longitudinal association of 25-Hydroxyvitamin D with adipokines and markers of glucose metabolism among Brazilian pregnant women

This study aimed to evaluate the longitudinal association of vitamin D status with glycaemia, insulin, Homeostatic Model Assessment of Insulin Resistance (HOMA-IR), adiponectin and leptin. A prospective cohort with 181 healthy, pregnant Brazilian women was followed at the 5th–13th, 20th–26th, and 30th–36th gestational weeks. In this cohort, 25(OH)D plasma concentrations were analysed using liq¬uid chromatography-tandem mass spectrometry. Vitamin D status was categorized as sufficient or insufficient using the Endocrine Society Practice Guidelines (ES) (≥75/<75 nmol/L) and the Institute of Medicine (IOM) (≥50/<50 nmol/L) thresholds. Linear mixed-effect regression models were employed to evaluate the association between vitamin D status and each outcome, considering the interaction terms between vitamin D status and gestational age (P<0.1). At baseline, 70.7% of pregnant women had 25(OH)D levels <75 nmol/L and 16% had levels <50 nmol/L. Women with sufficient vitamin D status at baseline, using both the ES and IOM thresholds, presented lower glycaemia than those with insufficient 25(OH)D. Pregnant women with 25(OH)D concentrations <75 nmol/L showed lower insulin (β=-0.12; 95% CI -0.251, 0.009; P=0.069) and adiponectin (β=-0.070; 95% CI -0.150, 0.010; P=0.085) concentrations throughout pregnancy than those with 25(OH)D levels ≥75 nmol/L. Pregnant women with 25(OH)D <50 nmol/L at baseline presented significantly higher leptin concentrations than those with 25(OH)D levels ≥50 nmol/L (β=-0.253, 95% CI: -0.044; 0.550, P=0.095). The baseline status of vitamin D influences the biomarkers involved in glucose metabolism. Vitamin D sufficient women at baseline had higher increases of insulin and adiponectin changes throughout gestation than those who were insufficient.