Gestational diabetes mellitus (GDM) is a condition with hyperglycaemia first seen in pregnancy. GDM is still diagnosed in the late second or early third trimester, because accurate diagnostic approaches in first trimester are still lacking and increasing burden of non-communicable diseases in the country. New diagnostic approaches allow early assessment. To assess the efficacy of glycosylated fibronectin in detecting GDM. In this case control study the pregnant women coming to outpatient department were recruited based on inclusion and exclusion criteria. It was carried out at RajaRajeswari Medical College and Hospital between January 2024 to February 2025. The participant’s oral glucose tolerance test (OGTT) was done at 24 to 28 weeks. Diagnostic cut off value based on Diabetes in Pregnancy Study Group India is considered. Based on OGTT value participants were divided into GDM group and control group. Glycosylated fibronectin was estimated by enzymelinked immunosorbent assay. The concentration of glycosylated fibronectin level between the control and GDM group was analysed using unpaired t-test. The P-value was 0.0001 suggesting significant difference between GDM and control group.The area under the ROC curve equals 0.8096 suggesting that the power of the model to distinguish between two outcomes is excellent. R 2 value by the regression analysis in GDM group is 0.9813 whereas in control group it is 0.9991 suggesting that glycosylated fibronectin can be used to make accurate predictions. Glycosylated fibronectin is a very potent biomarker in early diagnosis of GDM.