Association between essential metal elements in the blood of pregnant women in the first trimester and gestational diabetes mellitus and the mediating role of inflammatory indicators.

OBJECTIVE: To evaluate the potential association between essential metal elements and gestational diabetes mellitus (GDM), and to explore whether inflammatory indicators play an intermediary role in the association between essential metal elements and GDM.

METHODS: This study included 4833 pregnant women who underwent early pregnancy examinations at Guangdong Women and Children Hospital between 2015 and 2022. Basic demographic information and peripheral blood samples were collected. Atomic absorption spectrometry was utilized to measure five essential metal elements, including iron (Fe), calcium (Ca), zinc (Zn), copper (Cu), and magnesium (Mg) in whole blood samples of pregnant women. Routine blood tests, including white blood cell (WBC), lymphocyte (Lym), neutrophil (Neu), monocyte (Mono), and platelet (PLT), were conducted using an automated hematology analyzer. The generalized linear regression model (GLM) was employed to analyze the relationship between essential metal elements, inflammatory indicators, and GDM. Mediation analysis was used to explore the potential mediating role of inflammatory indicators in the association between essential metal elements and GDM.

RESULTS: Fe was positively correlated with WBC, NEU, LYM and MONO levels, and negatively correlated with PLT levels (P < 0.05). Ca was negatively correlated with WBC, NEU and MONO levels, and positively correlated with PLT levels (P < 0.05). Zn was positively correlated with WBC, NEU, LYM and PLT levels (P < 0.05). Cu was positively correlated with WBC, NEU and PLT levels (P < 0.05). Mg was positively correlated with WBC, NEU, LYM, MONO and PLT levels (P < 0.05). Compared with the first quantile concentration level, the fourth quantile level of Fe (OR = 1.282, 95 %CI: 1.043-1.578) and the fourth quantile level of Zn (OR = 1.267, 95 %CI: 1.032-1.559) were significantly positively correlated with GDM. WBC, NEU, LYM, MONO and PLT were all positively correlated with GDM risk (P < 0.05), and the correlation between five inflammatory indicators and GDM risk was positively linear by RCS (Poverall < 0.05 and Pnonlinear > 0.05). All five inflammatory indicators had significant mediating effects in the association between essential metal elements and GDM. Among them, the percentage of mediating effect of WBC was 29.18 % (OR = 1.043, 95 %CI: 1.027-1.061); The percentage of NEU mediating effect was 26.97 % (OR = 1.039, 95 %CI: 1.025-1.058); The percentage of LYM mediating effect was 8.30 % (OR = 1.012, 95 % CI: 1.004-1.023); The percentage of MONO mediation effect was 6.84 % (OR = 1.010, 95 % CI: 1.004-1.021); The percentage of PLT mediating effect was 8.87 % (OR = 0.987, 95 %CI: 0.976-0.995).

CONCLUSION: The study found a significant association between essential metal elements and GDM. Specifically, higher levels of Fe and Zn in pregnant women were positively associated with GDM. Furthermore, inflammatory indicators were identified to play a mediating role in the association between Fe levels and GDM. These suggested the imbalance of essential metal elements may increase the risk of GDM by influencing the levels of inflammatory indicators.