Objectives: To determine some risk factors and serum glucose concentrations by 75-g oral glucose tolerance test in gestational diabetes patients. Subjects and methods: A cross - sectional descriptive studied on 60 gestational diabetes mellitus (GDM) at National Endocrinology Hospital. Results: The study results showed: The average of age was 30.32 ±4.74 years, (mainly 26-30 years old (40%)), pregnancy period was mainly 25-34 weeks (63.3%). The rate of risk factors: overweight/obese prepregnancy was 71.7%; age (> 35 years old) was 26.7%; family history of diabete was 10%; polycystic ovaries was 6.7%; gestational diabetes history was 3.4%; previous foetal macrosomia> 4000g was 1.7%. The prevalence of increasing in M0 was 36.7%, M1 was 66.7% and M2 was 71.1%. the one of three was 25.0%, the two of three was 45% and all of M0, M1 and M2 was 30.0%. There is a possitiverelation between maternal weightand fasting glucose(Mo). Multivariable analysis showed that there were arelationships between height and age of mothers and serum glucose M0 and M1. Conclusion: Pregnant woman suffered from gestational diabetes, which was mainly atweek of 25 - 34 (63.3%). The main risk factor of GDM was overweight/obesity prepregnancy (71.7%). There were relationships between weight, age and height of pregnant woman and serum glucose level.