Background and Objective: Liver plays an important role in regulating glucose levels in the body. The liver enzyme gamma-glutamyl transferase (GGT), is a common marker of liver function and has also been associated with insulin resistance, which can be a precursor to gestational diabetes and type 2 diabetes. The aim of this study was to evaluate serum GGT in gestational diabetics. Materials and Methods: The cross sectional study was conducted between department of biochemistry and gynecology during Junes to November, 2016 in Erbil city. Blood specimens were collected in the diabetic center in Maternally Teaching Hospital after diagnostic by gynecologist. A total 50 cases were considered as Group I (GDM) and 50 were Group II controls (normal healthy pregnant women). Patient group also subdivided into three subgroups; subgroup 1 GDM first time, subgroup 2 GDM second time and subgroup 3 regard as diabetic patient type2. Results: There were statistically significant differences at the level (p value <0.001) elevations in serum GGT in GDM compared with control group, also uric acid, and calcium were increased in GDM. Conclusions: Our finding showed that increase serum GGT level is an independent risk factor for GDM and identified as high risk factor for GDM.