Gestational diabetes mellitus: relationship of adverse outcomes with severity of disease.

Abstract

Aims: To derive accurate estimates of risk of maternal and neonatal complications in women with gestational diabetes mellitus (GDM) and to investigate the association of the effect size of these risks on subgroups of GDM managed with dietary modification, metformin and insulin therapy.

Methods: This was a large retrospective cohort study undertaken at a large maternity unit in the United Kingdom between January 2010 and June 2022. We included singleton pregnancies that booked at our unit at 11-13 weeks' gestation. The rates of maternal and neonatal complications in pregnancies with GDM that were managed by a multidisciplinary team (MDT) in the specialist high-risk clinic were compared to those in non-diabetic pregnancies. We stratified pregnancies with GDM into those that were managed with diet, metformin and insulin to pregnancies without diabetes. Logistic regression analysis was carried out to determine risks of pregnancy complications in pregnancies with GDM and its treatment subgroups. Risks were expressed as absolute risks (AR) and odds ratio (OR) (95% confidence intervals [CI]). Forest plots were used to graphically demonstrate risks.

Results: The study population included 51,211 singleton pregnancies including 2089 (4.1%) with GDM and 49,122 (95.9%) controls without diabetes. In pregnancies with GDM, there were 1247 (59.7%) pregnancies managed with diet, 451 (21.6%) with metformin and 391 (18.7%) who required insulin for maintaining euglycaemia. Pregnancies with GDM had higher maternal age, body mass index (BMI), higher rates of Afro-Caribbean and South Asian racial origin and higher rates of chronic hypertension. In pregnancies with GDM compared to non-diabetic controls, there was an increased rate of preterm delivery, delivery of LGA neonate, polyhydramnios, preeclampsia, need for IOL, elective and emergency CS and PPH whereas the rate of delivery of SGA neonates and likelihood of an unassisted vaginal delivery were lower. In pregnancies with GDM, there is significantly increased risk of maternal and neonatal complications in those that require insulin compared to those that are managed on dietary modification alone.

Conclusions: There is a linear association between the risk of adverse outcomes and the severity of GDM with those on insulin treatment demonstrating an increased association with complications compared to those that have milder disease requiring only dietary modification.