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The prognostic value of the oral glucose tolerance test for future type-2 diabetes in nulliparous pregnant women testing negative for gestational diabetes


Aim — To determine the prognostic value of the antepartum 75g-oral glucose tolerance test (OGTT) for future type 2 diabetes mellitus (T2DM) in nulliparous pregnant women who tested negative for GDM.

Methods — A population-based retrospective cohort study of nulliparous pregnant women who underwent testing for GDM using a 75g-OGTT in Ontario, Canada (2007-2017). The overwhelming majority of women in Ontario undergo screening using the preferred 2-step approach where the 75g-OGTT is performed following an abnormal non-fasting 1-hour 50g-glucose challenge test. The relationship between the 75g-OGTT results in women who tested negative for GDM (defined as normal glucose at fasting, 1 and 2 hours post 75g-glucose load) and future T2DM (as recorded in the Ontario Diabetes Database by the end date of follow up period) was explored.

Findings — Of the 162,622 women who underwent 75g-OGTT during the study period, there were 41,507 (75.0%) who met the study criteria. In women without GDM, the adjusted hazard ratios (aHR) for T2DM were: at fasting 2.82 (95%-CI 2.18-3.64), at 1-hour 1.26 (1.15-1.37), at 2-hours 1.14 (1.04-1.25) for a 1 mmol/l increase in glucose. A model that combined all 3 OGTT values and clinical characteristics could detect 43% (42.6%-43.4%) of those who developed T2DM at 5-years post the index pregnancy for a false-positive rate of 20%.

Interpretation — The results of the antepartum OGTT can be used to refine the future risk of T2DM even in nulliparous pregnant women who tested negative for GDM.



Hiersch L, Shah BR, Berger H, Geary M, McDonald SD, Murray-Davis B, Halperin I, Fu L, Retnakaran R, Barrett J, Melamed N; For DOH NET (Diabetes Obesity And Hypertension In Pregnancy Research Network) and SOON (Southern Ontario Obstetrical Network Investigators)TM. Diabetes Metab. 2022; Jun 2 [Epub ahead of print].

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