Utility of antenatal clinical factors for prediction of postpartum outcomes in women with gestational diabetes mellitus (GDM)

Background: Gestational diabetes mellitus (GDM) is associated with life-long increased risk of type 2 diabetes: affected women are advised to undergo oral glucose tolerance testing (OGTT) at 6-12 weeks postpartum, then glucose screening every 1-3 years.

Aims: We investigated whether in women with GDM, antenatal clinical factors predicted postpartum abnormal glucose tolerance and compliance with screening.

Materials and methods: In women with GDM delivering 2007 to mid-2009 in a single hospital, antenatal/obstetric data and glucose tests at 6-12 weeks postpartum and during 5.5 years post-pregnancy were retrospectively collected. Predictors of return for testing and abnormal glucose tolerance were identified using multivariate analysis.

Results: Of 165 women, 117 (70.9%) returned for 6-12 week postpartum OGTT: 23 (19.6%) were abnormal. Smoking and parity, independent of socioeconomic status, were associated with non-return for testing. Fasting glucose ≥ 5.4 mmol/L on pregnancy OGTT predicted both non-return for testing and abnormal OGTT. During 5.5 years post-pregnancy, 148 (89.7%) women accessed glucose screening: nine (6.1%) developed diabetes, 33 (22.3%) had impaired fasting glucose / impaired glucose tolerance. Predictors of abnormal glucose tolerance were fasting glucose ≥ 5.4 mmol/L and 2-h glucose ≥ 9.3 mmol/L on pregnancy OGTT (~2.5-fold increased risk), and polycystic ovary syndrome (~3.4 fold increased risk). Risk score calculation, based on combined antenatal factors, did not improve predictions.

Conclusions: Antenatal clinical factors were modestly predictive of return for testing and abnormal glucose tolerance post-pregnancy in women with GDM. Risk score calculations were ineffective in predicting outcomes: risk scores developed in other populations require validation. Ongoing glucose screening is indicated for all women with GDM.