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

Aims: It is unclear whether patients diagnosed with early gestational diabetes mellitus (GDM) (<24 weeks) are at higher risk of diabetes mellitus (DM) in the postpartum period compared to those with standard GDM (diagnosed >= 24 weeks). This study assessed if rate of DM diagnosed postpartum differs among patients with early versus standard GDM. Methods: PubMed, EMBASE, WHO ICTRP, Clinicaltrials.gov and Cochrane Central Register of Controlled Trials were searched from inception to March 2023. Randomized controlled trials or observational studies that assessed rate of postpartum DM among patients with early GDM were included. Primary outcome was rate of DM diagnosed postpartum. Secondary outcomes were postpartum visit attendance, completion and results of postpartum oral glucose tolerance testing, and glycated hemoglobin (HbA1c) levels. Results: Of 5682 studies screened, 11 met inclusion criteria (N = 1573 early GDM vs. N = 3340 standard GDM). Patients with early GDM had mean age of 30.2-37.0 years and mean body mass index (BMI) of 24.4-35.6 kg/m2, while the standard group had a mean age of 28.9-32.8 years and mean BMI of 23.6-36.0 kg/m2. Most studies evaluated postpartum glucose tolerance at 5-12 weeks, though one followed patients up to six years postpartum. Overall, patients with early GDM were more likely to be diagnosed with DM postpartum than those with standard GDM (12.8 % vs. 6.1 %, RR 1.89, 95 % CI 1.10-3.24). Impaired glucose tolerance was also higher in patients with early GDM (24.7 % vs. 13.0 %, RR 1.84, 95 % CI 1.32-2.57). Conclusions: Rate of DM diagnosed postpartum was higher in patients with early GDM compared to standard GDM.