Background: Gestational diabetes mellitus (GDM) can influence the metabolic health of both mothers and their children in the long-term. However, it remains unknown whether initiating treatment early can have an impact on the future health of mothers and their infants. We conducted a follow-up study of the diabetes status of women participating in the Treatment Of BOoking Gestational diabetes Mellitus (TOBOGM) study for a duration ranging from 6 months to 4 years following childbirth.

Methods: All women consenting to participate in TOBOGM were eligible for follow up, including those with GDM diagnosed and treated early (“early GDM”), those with untreated early GDM and an oral glucose tolerance test (OGTT) at 24-28 weeks’ gestation (“deferred group”), those with no early GDM but GDM at the later OGTT (“late GDM"), those with no GDM (“normal”) and women with high fasting glucose (HFG) or overt diabetes in pregnancy (ODIP).  Contact details were fully available for 5 TOBOGM sites, all in NSW.  Consenting women were given a 20-item questionnaire to collect information related to postpartum diabetes screening, anthropometric measurements, medication and hospitalization history, as well as developmental milestones of their offspring. Surveys were carried out through telephone interviews or email invitations using REDCAP.

Results: Among the 855 identified participants, 463 (54.2%) completed the survey. Postpartum diabetes screening was carried out by 201 (44.9%): early GDM 31 (35.6%), deferred group 24 (48%), late GDM 27 (50.9%), normal GTT 112 (45.7%), and HFG/ODIP 7 (53.8%), p = 0.34). Screening rate was comparable for both the GDM and HFG/ODIP groups (43.2% vs.53.8%, p = 0.57). Among those screened, 41% underwent fasting blood glucose, 35% oral glucose tolerance test, and 16% HbA1c. Of those who underwent screening, 51.3% completed it within one year. Results showed that, when screened, diabetes had developed in no women with early GDM, in one with late GDM (3.7%) and in four (57.1%) from the HFG/ODIP group (p<0.001). In the deferred GDM group, two (8.3%) had developed impaired glucose tolerance or impaired fasting glucose. Of the “normal” group, three (2.7%) subsequently developed diabetes, while one (0.9%) developed impaired fasting glucose.

Conclusion: The rate of postpartum diabetes screening was insufficient among these participants in the TOBOGM study. Further follow-up is necessary to determine the impact of early treatment on the later metabolic health of TOBOGM participants and their offspring.