Usefulness of cutoff points of the IADPSG criteria for prediction of postpartum diabetes and prediabetes among Chinese women with gestational diabetes

Aims This study tests whether cutoff points of the International Association of Diabetes and Pregnancy Study Group's (IADPSG) criteria had threshold effects on postpartum prediabetes and diabetes among Chinese pregnant women with gestational diabetes mellitus (GDM). Materials and methods A total of 507 out of 1000 women with GDM (948 of them enrolled in a lifestyle trial during pregnancy) turned up for the follow-up study and underwent a 75-g 2-h OGTT. GDM was diagnosed based on the IADPSG's criteria while postpartum diabetes and prediabetes were defined by the World Health Organization's. Generalized logit model was used to obtain odds ratios (OR) and 95% confidence interval (CI) of fasting, 1-h and 2-h PGs for postpartum diabetes and prediabetes. Restricted cubic spline was used to identify any threshold effects. Results At a median of 9.1 weeks postpartum, 3.7% (n=19) women developed postpartum diabetes and 35.1% (n=178) developed postpartum prediabetes. Fasting PG ≥5.1 mmol/L was associated with markedly increased risk of postpartum diabetes without a discernible threshold (adjusted OR: 3.87, 95%CI: 1.03-14.52) while 2-h PG ≥8.5 and ≥9.0 mmol/L had threshold effects on postpartum prediabetes (2.10, 1.33-3.30) and diabetes (4.02, 1.04-15.56). The 1-h PG also had a threshold at ≥10.0 mmol/L for prediabetes (1.67, 1.06-2.64) but it was not significant for postpartum diabetes. Conclusions Among Chinese women with GDM, fasting PG ≥5.1 mmol/L was associated with postpartum diabetes without any discernible threshold effects while 2-h PG ≥8.5 and ≥9.0 mmol/L respectively identified women at high risk of postpartum prediabetes and diabetes. This article is protected by copyright. All rights reserved.