Background: Gestational diabetes mellitus (GDM) is a widely common condition that is defined as glucose intolerance of relatively different degrees, and it affects pregnant women. In a recent study performed in Turkey, the authors found a higher risk of GDM for the patients with blood group AB. Aim: This study was done to detect the association of blood group type and the incidence of GDM. Materials and Methods: A retrospective study was carried out in 2016 in a group of GDM patients at King Abdulaziz University Hospital (KAUH). Patients were identified using the electronic medical records’ system. Results: The percentages of patients with GDM for O, A, B, and AB groups were 43.8%, 33.7%, 16.3%, and 6.2%, whereas those of control group (healthy donors) were 38.20%, 33.90%, 24.9%, and 3%, respectively. In both groups, the ratio of the patients with blood group O was the highest, while the ratio of group AB was the lowest. Blood group AB was found to be higher in the patients with GDM compared to the control group. Conclusion: Women with AB blood group might have a higher risk of developing GDM. More studies are needed to confirm the finding in this study.