Toxoplasmosis is a parasitic infection caused by Toxoplasma gondii. Immunocompromised individuals and pregnant women are at risk, with the latter group being susceptible to miscarriages. This study aimed to determine the seropositivity of T. gondii antibodies and potential risk factors in pregnant women diagnosed with diabetes mellitus. The research was conducted at the Ankara City Hospital Perinatology Clinic between October 2021 and June 2022. The study included 277 pregnant women diagnosed with diabetes mellitus and 277 healthy pregnant women who had given birth. Retrospective analysis of anti-T. gondii immunoglobulin (Ig)G and IgM levels was performed for patients between January 2020 and February 2022. Participants were administered an informed consent form and a questionnaire. Data were analysed using SPSS 22. Among pregnant women with diabetes, IgG seropositivity was 18.4%, IgM was 0.0%, and IgG+IgM was 0.0%. In healthy pregnant women, IgG seropositivity was 12.3%, IgM was 0.4%, and IgG+IgM was 0.4%. Overall, seropositivity rates were 15.3% for IgG, 0.2% for IgM, and 0.2% for IgG+IgM. The difference between the two groups was statistically significant (p<0.05). Among pregnant women with diabetes, there was a significant statistical difference (p<0.05) in anti-T. gondii IgG seropositivity related to education, employment status, number of pregnancies and live births, history of toxoplasmosis diagnosis in children, previous toxoplasmosis diagnosis, hygiene, nutrition, and social habits. Among healthy pregnant women, significant statistical differences were found (p<0.05) in IgG seropositivity related to age, income, education level, number of pregnancies and live births, previous toxoplasmosis diagnosis, hygiene, nutrition, and social habits. No invasive interventions were performed on infants born to seropositive mothers, and perinatal data were not available. The seroprevalence of toxoplasmosis in Ankara appears to be decreasing, but T. gondii infections continue to pose a public health concern and are significant in pregnant women with diabetes mellitus.