Cardiometabolic Outcomes in Women With Overt Diabetes at Diagnosis Versus Gestational Diabetes: A Systematic Review and Meta-Analysis

Women diagnosed with hyperglycemia in pregnancy represent a heterogeneous population. A distinct subgroup, those with overt diabetes or diabetes in pregnancy (DIP) diagnosed at the first prenatal visit or during pregnancy (fasting plasma glucose (FPG) ≥ 7.0 mmol/L or glycated hemoglobin (HbA1c) ≥ 6.5%), may carry a significantly higher long-term cardiometabolic risk than women with standard gestational diabetes mellitus (GDM). This study aimed to review and meta-analyse the risk of postpartum type 2 diabetes mellitus (T2DM), metabolic syndrome (MetS), and cardiovascular risk markers in women diagnosed with overt diabetes during pregnancy compared to those with GDM. PubMed/MEDLINE, Embase, Web of Science, and Cochrane Library were searched from inception to December 2025. Observational studies comparing maternal postpartum cardiometabolic outcomes between women with overt diabetes (excluding known pre-existing diabetes) and women with GDM were included. Two independent reviewers extracted data and assessed quality using the Newcastle-Ottawa Scale and JBI checklists. Random-effects meta-analysis with Hartung-Knapp-Sidik-Jonkman adjustment was performed. The primary outcome was incident postpartum T2DM. Certainty of evidence was evaluated using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach. Seven studies (n = 3,293 participants) from Asia, Africa, Oceania, and Europe met the inclusion criteria. Women with overt diabetes had a substantially increased risk of developing postpartum T2DM compared to women with GDM (pooled odds ratio (OR) 10.69; 95% CI 5.32-21.48; <i>p</i> < 0.001; high certainty evidence). They exhibited a more than two-fold higher risk of MetS (OR 2.29; 95% CI 1.49-3.53; <i>p</i> < 0.001; moderate certainty evidence). Mean BMI was numerically higher in the overt diabetes group (mean difference 1.60 kg/m ²), though not statistically significant (<i>p</i> = 0.07). Heterogeneity was negligible for the primary outcome (I² = 0.5%). These findings support the urgent need for stratified postpartum surveillance and intensive, early preventive interventions for women with overt diabetes, rather than managing them under general GDM protocols.