Discordance Between Ogtt-Based Glycemic Classification and Recorded Gestational Diabetes Diagnosis: A Secondary Reclassification Analysis

Background: Different diagnostic approaches for gestational diabetes mellitus (GDM) may classify the same pregnantwoman differently. This study assessed agreement between recorded GDM diagnosis and reconstructed classification usingInternational Association of Diabetes and Pregnancy Study Groups (IADPSG) glucose thresholds. Materials and Methods:This secondary reclassification analysis included 100 pregnant women. Reconstructed IADPSG positivity was defined asfasting glucose ≥92 mg/dL, 1-hour glucose ≥180 mg/dL or 2-hour glucose ≥153 mg/dL. Agreement with recorded GDMstatus was assessed using overall agreement, Cohen’s kappa and McNemar’s test. Participants were classified into fourconcordant or discordant diagnostic groups. Clinical characteristics and pregnancy outcomes were compared and adjustedrelative risks were estimated using modified Poisson regression. Results: IADPSG criteria classified 66 women as positivecompared with 46 having recorded GDM. Thirty-eight participants were positive by both methods and 26 were negative byboth. Twenty-eight were IADPSG positive without recorded GDM, while eight had recorded GDM despite being IADPSGnegative. Overall agreement was 64.0% with a Cohen’s kappa of 0.298. McNemar testing showed significant discordance(p=0.0015). Fasting, 1-hour and 2-hour glucose differed significantly across diagnostic groups (all p<0.001). However,preterm delivery, core adverse pregnancy outcome and perinatal composite did not differ significantly. Adjusted outcomerisks were also not significant. Conclusion: Reconstructed IADPSG criteria produced substantial reclassification comparedwith recorded GDM status. The discordance was mainly due to additional IADPSG-positive women, without a cleardifference in adjusted pregnancy outcomes.