Background <p>Psychiatric disorders are severe mental illnesses associated with insulin resistance, systemic inflammation, and neurohormonal dysfunction. To synthesize the available evidence and provide recommendations for the clinical management of this patient population, this study aimed to comprehensively examine and meta-analyze the association between bipolar disorder, schizophrenia, and the risk of gestational diabetes mellitus (GDM).</p> Method <p>A systematic search was conducted in PubMed, Embase, Scopus, Web of Science, and Google Scholar. Studies reporting an association between pre-pregnancy bipolar disorder or schizophrenia and GDM were included. Random-effects models were used for meta-analysis, and risk ratios (RRs) with 95% confidence intervals (CIs) were calculated.</p> Results <p>Among 10 eligible studies, the meta-analysis revealed that women with bipolar disorder (RR: 1.59; 95% CI: 1.13–2.23) and schizophrenia (RR: 2.07; 95% CI: 1.39–3.07) had a significantly higher risk of developing GDM. Evidence regarding this association after controlling for confounding factors was limited. however, pooled analysis of the few available studies showed RRs of 1.43 (95% CI: 0.83–2.38) for bipolar disorder and 1.29 (95% CI: 1.07–1.55) for schizophrenia.</p> Conclusions <p>This study provides evidence that bipolar disorder and schizophrenia are associated with an increased risk of gestational diabetes. Regular screening and management of modifiable risk factors, alongside mental health stability, are essential in women of reproductive age. Future prospective studies should investigate the underlying mechanisms of this association.</p>