Aim: To determine the relationships between maternal and fetal outcomes and gestational diabetes mellitus (GDM), impaired fasting glucose (IFG) and impaired glucose tolerance (IGT), respectively. Methods: A retrospective cohort study design was used with 149 patients with abnormal oral glucose tolerance test (OGTT) and 149 normal patients. Statistical analysis used was the chi-squared test, Fisher’s exact test or the Student’s t -test, as appropriate. P<0.05 was considered significant. Results: The level of hyperglycemia according to the OGTT (World Health Organization criteria) was associated with pre-eclampsia, polyhydramnios and macrosomia in GDM patients. There was no increase in the complications of preterm labor and premature rupture ...