Assessment of Serum Ferritin, CRP and Insulin Levels in First Trimester of Pregnancy as a Predictive Biomarker of Gestational Diabetes Mellitus: A Longitudinal Study

Introduction: Gestational Diabetes mellitus (GDM) increases the risk of foetal morbidity and mortality heralding the future risk of development of type 2 diabetes in mother. GDM develops mainly due to insulin resistance along with interplay of risk factors like advancing maternal age, family history of diabetes, obesity, ethnicity, history of macrosomia. Aim: To detect whether estimation of serum ferritin, C-reactive protein and insulin in 1st trimester can predict the subsequent occurrence of GDM and whether susceptible mothers can be managed cautiously to prevent foeto-maternal complications. Materials and Methods: This hospital-based longitudinal study was done in Department of Gynaecology and obstetrics in collaboration with the Department of Biochemistry, Medical College and Hospital, Kolkata, West Bengal, India, from January 2018 to June 2019. The study included 80 antenatal mothers attending the Antenatal Outpatient Department in first trimester. The blood samples were collected from them during first trimester and serum ferritin, C-reactive Protein (CRP) and insulin were estimated using different methods as specified later. The anthropometric measurements of the mother {Body Mass Index (BMI), skin fold thickness and waist hip ratio} were measured. These enrolled study participants have undergone Oral Glucose Tolerance Test (OGTT) with 75 gm of anhydrous glucose at 24-28 weeks of gestation. The performance parameters like sensitivity, specificity, positive predictive value, negative predictive value and likelihood ratio of ferritin and CRP was calculated. Results: The mean age of participants who developed diabetes (n=12) 25.75 +/- 2.92 and who did not developed diabetes (n=68) 23.91 +/- 3.74 years. There was 15% prevelance of GDM in study population. The median concentration of serum ferritin and CRP was significantly higher in patients who developed GDM (n=12) among the study population (n=80). The sensitivity of serum ferritin {83.33% (95% confidence interval=51.59-97.91%)} was higher in comparison to C-reactive protein {31.82% (95% CI=13.86-54.87%)}. Conclusion: There was a remarkable decline of insulin sensitivity with the advancement of pregnancy. This implies that latent insulin resistance may start from first trimester and screening in high risk ethnicity group like India should be a routine protocol.