Diagnostic Accuracy of Glycated haemoglobin, markers of insulin resistance, B cell function and insulin sensitivity in Gestational Diabetes mellitus keeping Oral glucose tolerance test as gold standard

Objective: To evaluatethe diagnostic accuracy of glycated haemoglobin (HbA1c), marker of insulin resistance (HOMA-IR), B cell function (HOMA-B) and Quantitative insulin sensitivity check index (QUICKI) in gestational diabetes mellitus (GDM). Study Design: Cross-Sectional comparative study. Place and Duration: Clinical chemistry and Endocrinology section of Pathology department, Combined military hospital, Lahore, from 01st March to 31st August 2023. Methodology: A total of 250 females underwent OGTT for GDM. Blood samples were analyzed for plasma glucose, HbA1c, and insulin, with subsequent calculation of Homeostatic model assessment for insulin resistance (HOMA-IR), HOMA-B, and QUICKI. Receivers operating curve (ROC) was made, cutoffs were derived from it and diagnostic accuracy parameters were calculated for the cutoffs. Results: The median HbA1c was significantly higher, in the GDM group (5.80 %) than in females with NGT (5.0 %) (p<0.001). Sensitivity and Specificity for HbA1c at cut off of 5.25 was 84% and 76% and for 5.65 was 63% and 95% respectively. Additionally, GDM patients showed higher median values of fasting insulin (12.30 IU/ml), HOMA-IR (2.95), and lower median QUICKI values (0.323) compared to females with NGT (n=183), with values of fasting insulin 6.0 IU/ml, HOMA-IR 1.20 and QUICKI 0.370, respectively (p <0.001).HOMA-IR at cutoff of 1.45 has 94% sensitivity and 60% specificity. Conclusion: HbA1c proves valuable as a specific test at the 5.65% cutoff, but a more sensitive test should complement it for effective GDM detection. HOMA-IR at a cutoff of 1.45 presents 94% sensitivity and a negative predictive value (NPV) of 98%. However, being less specific, individuals with HOMA-IR > 1.45 should be advised OGTT for GDM confirmation. Keywords: American Diabetes Association, Diagnostic Accuracy, Gestational Diabetes Mellitus, Glycated Haemoglobin, Insulin Indices, Oral Glucose Tolerance Test. How to Cite This: Khan NU, Anwar H, Rana MZ, Sattar A. Diagnostic Accuracy of Glycated haemoglobin, markers of insulin resistance, B cell function and insulin sensitivity in Gestational Diabetes mellitus keeping Oral glucose tolerance test as gold standard. Isra Med J. 2024; 16(2): 36-41. DOI: https://doi.org/10.55282/imj.oa1401