Utility of in-hospital post-delivery fasting plasma glucose to predict postpartum glucose status in women with hyperglycaemia first detected in pregnancy: A prospective cohort study

BACKGROUND: Women with hyperglycaemia first detected in pregnancy (HFDP), including those with gestational diabetes mellitus (GDM), should undergo a glucose evaluation 4–12 weeks after delivery. Globally, suboptimal postpartum return rates limit the opportunity to intervene in women with sustained hyperglycaemia and pragmatic solutions should be sought to bridge this gap. OBJECTIVE: To assess the utility of postpartum in-hospital glucose evaluation to predict the outcome of the oral glucose tolerance test (OGTT) performed 4–12 weeks after delivery. METHODS: The study was performed prospectively at Tygerberg Hospital, Cape Town, South Africa. Women with HFDP, classified as GDM based on the modified National Institute for Health and Care Excellence criteria, who delivered between November 2018 and June 2019 were included in the study. Fasting plasma glucose (FPG) was performed 24–72 hours after delivery (t1) in the postnatal ward, provided glucose lowering medication was discontinued at delivery. An OGTT 4–12 weeks postpartum (t2) was scheduled for the total cohort. We compared glucose values and glucose categories at t1 and t2 and evaluated antenatal characteristics of women who returned, compared to the group that was lost to follow-up. RESULTS: In-hospital post-delivery glucose assessment (t1) was performed in 115 women. Glucose levels were significantly lower at t1 compared to antenatal diagnostic values (t0) and assessment at t2. Of the fourteen women with hyperglycaemia at t2, none had abnormal fasting glucose concentrations at t1. Women with HFDP who fulfilled criteria for overt diabetes at t0, all (24/115) had normal fasting glucose levels at t1 except for IFG in one (1/24). The antenatal characteristics of women with HFDP who returned at t2, were similar to the women who did not return. CONCLUSION: Based on this study, in-hospital fasting glucose 24–72 hours postpartum cannot replace the OGTT 4–12 weeks postpartum. Pragmatic solutions for low postpartum return rates in women with HFDP should be pursued.