Maternal Serum Copper and Some Metabolic Indexes in Late Second Trimester of Gestational Diabetes Mellitus Pregnancy

BACKGROUND: Copper (Cu) is a physiologically important trace element during pregnancy. The study aim is to assess the altered level of serum Cu and its association with some metabolic indexes in Gestational Diabetes Mellitus (GDM). METHODS: A total of 108 pregnant women (aged 18 - 40, second trimester) are included in the study and divided into two groups (GDM n = 54; pregnant with normal glucose tolerance (NGT), n = 54) after performing a 2-hour 75-g oral glucose tolerance test (OGTT). Maternal blood samples are collected at 26 - 28 gestational week. All biochemical parameters are measured in serum from fasting venous blood. Serum Cu levels are analyzed by flame atomic absorption spectrophotometry (Perkin Elmer AAnalyst 300, USA). Body Mass Index (BMI), insulin sensitivity/resistance, triglyceride-glucose (TyG), TyG-BMI (triglyceride glucose-body mass) indexes are calculated by formulas. RESULTS: The following data were observed: significantly higher levels of serum Cu (p = 0.009), pre-pregnancy BMI (pre-pBMI), BMI at the GDM diagnosis (pBMI), TyG, pregnancy TyG-BMI (pTyG-BMI) p < 0.001, and triglycerides (Tgl) (p = 0.02) in GDM compared to NGT pregnancy. The study presents a positive correlation between serum Cu and pre-pBMI (p < 0.02), pBMI and pTyG-BMI (p < 0.001). Besides, pre-pBMI (mean ≥ 25 kg/m2), pBMI (mean ≥ 30 kg/m2), and pTyG-BMI are associated with 14.5% (OR 1.145, 95% CI: 1.064 - 1.232; p < 0.001), 15.3% (OR 1.153, 95% CI: 1.070 - 1.243; p < 0.001), and 5.9% (OR 1.059, 95% CI: 1.022 - 1.086; p < 0.001) increased risk for GDM development. No association is found between Cu and Tgl levels, fasting plasma glucose e(FPG) and TyG. ROC analysis suggests the serum Cu as a possible risk factor for GDM development. The analysis shows that at a cutoff point of ≥ 31.9 µmol/L, serum Cu presents a sensitivity and specificity of 64.8% and 66.7% in the prediction of GDM development (AUC = 0.659, p < 0.012). After adjustment for maternal age, gestational age, and family predisposition, the odds ratios (ORs) (95% CIs) still show association of Cu levels with increased GDM risk (OR 1.099, 95% CI 1.018 - 1.184, p = 0.013). CONCLUSIONS: pTyG-BMI index exhibits a better interaction than TyG index, Tgl, and glucose separately with serum Cu levels where BMI has a mediator's role.