Agreement Between Immediate and Six-Week Postpartum Testing for Detecting Abnormal Glucose Tolerance in Women with Gestational Diabetes Mellitus.

Objective: To evaluate the prevalence of abnormal glucose tolerance at six weeks postpartum among women with gestational diabetes mellitus (GDM) and to evaluate the agreement between early postpartum and six-week postpartum oral glucose tolerance test (GTT). Methods: This prospective repeated-measures study included Thai women with singleton pregnancies, no pregestational diabetes, and a diagnosis of GDM. Participants were consecutively recruited upon admission to the labor and delivery unit. All participants underwent a 75 g, 2-hour GTT both during the immediate postpartum prior to hospital discharge and at six weeks postpartum. Glucose tolerance status was categorized as normal glucose tolerance and abnormal GTT. Agreement between the two testing periods was evaluated using Cohen's kappa coefficient. Results: A total of 158 women were included in the analysis. The prevalence of abnormal glucose tolerance at six weeks postpartum was 44.9% (71/158), including impaired GTT in 66 women (41.8%) and diabetes mellitus in 5 women (3.2%). Among women with abnormal GTT at six weeks postpartum, 42.3% (30/71) had normal early postpartum results. Conversely, 44.6% (33/74) of women with abnormal early postpartum findings demonstrated normal GTT at six weeks. The Cohen's kappa coefficient was 0.197, indicating poor agreement. Agreement for diabetes mellitus diagnosis was similarly low (kappa = 0.201). Conclusion: Early postpartum OGTT demonstrated poor agreement with six-week postpartum testing and showed limited utility as a standalone screening strategy for postpartum dysglycemia among women with GDM. Early postpartum testing may not accurately reflect glycemic status at 6 weeks postpartum, potentially leading to misclassification.