Screening for late‐onset gestational diabetes: Are there any clinical benefits?

To determine whether screening for gestational diabetes mellitus (GDM) in the third trimester and managing those who are screen positive on a diabetes pathway affects obstetric and neonatal outcomes.Retrospective study of prospectively collected data.London Teaching Hospital.A total of 14 366 women delivering between 1 January 2018 and 31 December 2020.Retrospective chart analysis.Diagnosis of late-onset GDM, obstetric and neonatal outcomes.Five hundred and thirty-one women were tested by home glucose monitoring for late-onset GDM from 33 weeks of gestation. In all, 244 were diagnosed as having GDM (group 1) and managed accordingly, and 287 (group 2) were returned to normal care. A total of 1415 women had GDM diagnosed by oral glucose tolerance test before 33 weeks of gestation (group 3). Of the women in group 2, 49.5% had a spontaneous onset of labour compared with only 25.8% and 27% in groups 1 and 3. However, women in group 2 were significantly more likely to have a macrosomic baby (≥4000 g, 25.4%) than groups 1 (16.0%) or 3 (7.2%), and their babies were more likely to be admitted to special care (5.2% versus 2% in group 1). Macrosomic babies were associated with significantly higher rates of shoulder dystocia, third- and fourth-degree tears and postpartum haemorrhage.Apparent late-onset GDM affects a significant proportion of women, and targeted intervention was associated with better obstetric and neonatal outcomes. These results suggest that all pregnancies with risk factors for late-onset GDM might benefit from active GDM management irrespective of specific glucose thresholds.Women with risk factors for GDM in the third trimester, and their babies, would probably benefit from active management of their blood sugars irrespective of threshold values.