(1178) Postpartum diabetes mellitus among patients with early gestational diabetes mellitus: A systematic review and meta-analysis

Objective: Patients diagnosed with early gestational diabetes mellitus (GDM) are commonly managed as pregestational DM. However, little is known whether early GDM is gestational or pregestational DM diagnosed in pregnancy. Our objective was to assess if the rate of DM diagnosed postpartum differs between patients with early GDM (< 24 weeks) and those with standard GDM (24-28 weeks).

Study Design: This was a systematic review and meta-analysis registered with Prospero (CRD42022372568). An electronic search was conducted of PubMed, EMBASE, World Health Organization International Clinical Trials Registry Platform, Clinicaltrials.gov, and Cochrane Library through March 2023. Randomized controlled trials (RCTs) or observational studies of postpartum patients with early diagnosis of GDM were included. The primary outcome was rate of DM diagnosed postpartum. DerSimonian-Laird method was used, results were presented as relative risk (RR), 95% confidence intervals (CI). Post-hoc subgroup analyses were performed for the primary outcome among studies in the USA, used 2-hour or 3-hour oral glucose tolerance test (oGTT) for GDM screening, and early GDM diagnosed at < 24 weeks or < 20 weeks.

Results: Of 5682 studies screened, 11 met inclusion criteria. Seven were prospective cohorts, two were retrospective cohorts and two were secondary analyses of RCTs. Of 1305 patients with early GDM, 248 (19.0%) had DM compared to 181 (6.1%) of 2972 with standard GDM (RR 1.89, 95% CI 1.10-3.24). This persisted for the primary outcome among studies in the USA (RR 2.04, 95% CI 1.53-2.73), used 3-hour oGTT (RR 1.95, 95% CI 1.31-2.90), and defined early GDM < 20 weeks (RR 2.31, 95% CI 1.09-4.87). However, this was no longer significant with studies that used 2-hour oGTT (RR 1.08, 95% CI 0.17-6.73) or defined early GDM < 24 weeks (RR 1.39, 95% CI 0.50-3.87).

Conclusion: The rate of DM diagnosed postpartum was higher in patients with early GDM compared to standard GDM diagnosis. Although at higher risk, the majority (81%) of patients with early GDM were not found to have DM postpartum. Thus, early GDM should not be a presumed diagnosis of DM.