Aim: To investigate the value of measuring liver enzymes, red cell distribution width (RDW), and mean platelet volume (MPV) in predicting the development of gestational diabetes mellitus (GDM). Materials and methods: The medical records of all pregnant women followed by the obstetrics clinic between January 2010 and November 2012 were systematically evaluated, and patients with a diagnosis of GDM were identified. A total of 68 patients with GDM and 61 healthy controls were included in the study. Results of relevant laboratory parameters were recorded. Results: Out of all the parameters evaluated, mean values for platelet distribution width (PDW) and mean activities of alanine transaminase (ALT) and γ-glutamyl transferase (GGT) were significantly higher in the GDM group compared to healthy controls (P = 0.003, P = 0.015, and P = 0.021, respectively), whereas mean plateletcrit (PCT) levels were significantly lower in the GDM group (P = 0.002). No significant difference was observed between groups in terms of MPV, RDW, platelet count, and aspartate transaminase levels. Conclusion: Our study results suggest that ALT, GGT, PCT, and PDW may be useful as predictors of impending GDM. © TÜBİTAK.