As part of normal physiological changes of pregnancy, there is increased insulin resistance, which causes dysregulation of maternal glucose homeostasis. Obesity, which is body mass index greater or equal to 30 kg/m2, is also associated with impaired glucose metabolism. Women with higher body mass index (BMI) usually have higher risk of developing gestational diabetes mellitus (GDM) than normal BMI women. The American Congress of Obstetricians and Gynecologists (ACOG) recommends early screening for gestational diabetes mellitus in certain categories of patients with higher risk factors which includes previous medical history of gestational diabetes mellitus, known impaired glucose metabolism and obesity.