Early gestational hyperglycemia in Bangladesh: discordance between IADPSG and ADA diagnostic criteria

The American Diabetes Association (ADA) and International Association of Diabetes and Pregnancy Study Groups (IADPSG) frameworks differ in their approach to hyperglycemia detected in early pregnancy. This study compared glycemic classification and agreement between the ADA framework and the IADPSG-derived glucose thresholds adopted by the World Health Organization (WHO) in 2013 (IADPSG/WHO framework) across gestational-age strata in a Bangladeshi cohort. In this cross-sectional study conducted from May 2023 to January 2025, 753 pregnant women attending a tertiary-care gestational diabetes mellitus (GDM) clinic underwent a three-sample 75-g oral glucose tolerance test (OGTT). Glycemic status at the index OGTT was classified according to the IADPSG/WHO and ADA 2023 frameworks within three gestational-age strata: <15 weeks, 15–23 weeks, and ≥ 24 weeks. Agreement was assessed using Cohen’s kappa after dichotomizing glycemic status as normal or abnormal, while paired differences were evaluated using McNemar’s test. Among 753 participants (median age 27.0 years; median BMI 26.5 kg/m²), 66 underwent the index OGTT before 15 weeks, 220 at 15–23 weeks, and 467 at ≥ 24 weeks. Before 15 weeks, observed binary agreement was 80.3% (κ = 0.595, approximate 95% CI 0.415–0.775). At 15–23 weeks, agreement was 69.5%, although κ was low (κ = 0.091, approximate 95% CI 0.015–0.167). In this group, 67 women classified as having abnormal glycemia by IADPSG/WHO were classified as normal by ADA (exact McNemar p < 0.001). From 24 weeks onward, classifications were identical (100% agreement; κ = 1.000). HbA1c was unavailable, potentially limiting ascertainment of ADA-defined early abnormal glucose metabolism. Agreement between the IADPSG/WHO and ADA frameworks varied substantially by gestational age, with the greatest classification discordance at 15–23 weeks and complete concordance from 24 weeks onward. These findings highlight gestational-age-dependent differences in glycemic classification; further prospective studies incorporating maternal and neonatal outcomes are needed to establish their clinical implications.