©J. A. Barth Verlag in Georg Thieme Verlag KG Stuttgart.Objective: To evaluate the association between cognitive functions and metabolic status in cases with gestational diabetes mellitus (GDM). Methods: In this study 44 patients with GDM and 45 normal pregnant were included. Depression was evaluated with Beck's depression inventory (BDI). Cognitive functions were evaluated with Montreal cognitive assessment (MOCA), paced auditory serial addition test (PASAT), spatial recall test (SRT), symbol digit modalities (SDMT), and word list generation (WLG). Results: The mean gestational age, educational level and account of previous birth of the subjects in the study were not statistically different between the groups. The mean scores of BDI of the 2 groups were not statistically different. MOCA score and SDMT was significantly decreased in GDM in comparison to NP (p=0.005, p=0.04 respectively). Also, SDMT score was inversely correlated with number of pregnancies, postprandial blood glucose and HbA1c.The scores of PASAT, SRT, SPART and WLG were statistically similar between the groups. Conclusions: Our findings may be a clue for early onset of impairment in cognitive functions in cases with new onset diabetes during pregnancy.