Many women develop postpartum mental health symptoms, ranging from the maternity blues to clinically diagnosed postpartum depression (PPD). Substantial literature supports an association between depression and type 2 diabetes, but there is limited literature regarding to what extent this relationship pertains to gestational diabetes (GDM) and postpartum depression. Review of the literature regarding GDM and PPD with a particular focus on describing the prevalence of PPD among women who may be at increased risk for GDM, including low-income and ethnic minority groups, was performed. Literature searches were conducted across four databases for studies reporting postpartum mental health outcomes (including postpartum depression, behavioral symptoms, mental disorders, mood, anxiety, quality of life) following a diagnosis of GDM. Studies including subgroups of women with GDM were included if postpartum mental health outcomes were reported. Of the 245 abstracts identified, ten studies were included in the final review. Findings suggest that PPD was high among low-income, ethnic minority women. Additional research is required to understand the complex relationship between GDM and PPD among low-income women, with the ultimate goal of implementing tailored interventions to address their medical and psychiatric needs.