Abstract Gestational diabetes (GDM) increases the risk of type II diabetes and cardiovascular morbidity later in life but GDM incidence in women from different cultural backgrounds varies. This study aims to examine treatment of GDM and pregnancy outcomes in Somali, Kurdish and general population women. Patient data of 312 Kurdish, 254 Somali and 508 general population women was collected from Turku University Hospital records from 2008 to 2019. The general population was selected by randomization with matching year, BMI, age, and parity. Singleton deliveries after 34th gestational week with no prior diabetes mellitus were included. Descriptive and comparison analyses (SPSS, version 29.0) were used to identify associations between ethnic background and pregnancy outcomes in women with GDM. The incidence of GDM was 22 % (CI 95 % 17-27) in Somali, 36 % (CI 95 % 31-42) in Kurdish, and 16 % (CI 95 % 13-19) in the general population women. Kurdish women had medication for GDM more often (43 % CI 95 % 34-53) than the Somali (22 % CI 95 % 11-33) and general population women (18 % CI 95 % 9-26). Metformin was more commonly used among Kurdish (30 % CI 95 % 22-39) compared to the general population (12 % CI 95 % 4-18) and Somali women (13 % CI 95 % 4-22). There was no difference in insulin or combined metformin and insulin treatment between the groups. In GDM group, vaginal deliveries were more common in general population (89 % CI % 81-95) than in Somali women (67 % CI % 64-81). Induction of labour (indication GDM or other) and instrumental vaginal delivery rates were similar between the groups. Newborns of all Somali women had a lower weight (SD -0.3 CI 95 % -0.7 - -0.2) compared to the general population (SD 0 CI 95 % -0.1 - 0.3). The prevalence of GDM was increased and dietary treatment decreased in Kurdish women compared to the general population in Finland. In the future, the treatment of GDM should be adjusted to better optimize the care for different cultural background women. Key messages • Kurdish women have increased incidence of GDM and less dietary treatment compared to the general population with similar risk factors. The pregnancy outcomes remain good in all groups. • With Somali women, the birth weight of the child is lower despite GDM status. This might direct clinicians to underestimate the effect of GDM when considering individual treatment.