Introduction: Gestational diabetes mellitus (GDM) is a transitory form of diabetes (glucose intolerance) with onset or first recognition during pregnancy. It is a major and growing public health problem in most parts of the world, with a global prevalence of between 2% and 6% (and as high as 20% in high-risk populations). Gestational Diabetes Mellitus (GDM) is a metabolic disorder defined as glucose intolerance with onset or first recognition during pregnancy. These women are at increased risk of adverse maternal and fetal outcome. Therefore, it’s early diagnosis and management is essential for better fetomaternal outcome. Objective: To assess the prevalence, risk factors and its outcome of gestational diabetes mellitus. Materials and Methods: A Prospective hospital based study was carried out at Dept. of Obstetrics & Gynecology, Al Hera Hospital (Private Clinic), Mawna Chowrasta, Sreepur, Gazipur, Bangladesh from June to December 2021. They were given 75gm glucose irrespective of meals and after 2 hours plasma glucose was estimated. GDM was diagnosed when after 2hours plasma glucose was>140mg/dl. All patients with GDM were followed up and treated with diet and /or insulin therapy till delivery. Maternal and fetal risks factors and outcome were evaluated. Results: Prevalence of GDM was 8.2% in my study. Many of the cases diagnosed as GDM had previous history of large baby, still birth or spontaneous abortion. Maternal complications observed were PIH (40%), polyhydramnious (37.7%), while 66.6% had to undergo caesarean section. Preterm labour occurred in 4 case each (8.8%). No complications were observed in 8 cases (17.7%). 28.8% babies had birth weight of >3.5kg and 17.7% were below 2.5 kg. Conclusion: Women with GDM showed an increased risk of obstetrical and fetal complications. Estimation of plasma glucose level using DIPSI criteria is a single step and cost -effective test to screen large number of cases and to diagnose and manage GDM to prevent maternal and fetal complications.