Gestational diabetes mellitus (GDM) is the most common complication of pregnancy, with an incidence rate of 10-15% \[1\]. Common risk factors for GDM are increased maternal age and weight and as a consequence of women delaying childbirth and increasing incidence of obesity, there is a corresponding increase in the rate of GDM. GDM is associated with an increased risk of maternal and perinatal short and long-term complications . These include macrosomia, shoulder dystocia, neonatal hypoglycaemia, neonatal hyperbilirubinemia, and perinatal mortality. Maternal complications include higher risks of hypertensive disorders, perineal trauma, and caesarean section. Additionally, both the mothers with GDM and their infants have an increased risk of developing type 2 diabetes mellitus and cardiovascular disease later in life . Screening and diagnosis of GDM is currently based on an oral glucose tolerance (OGTT), which is carried out at 26-28 weeks' gestation. In addition, an OGTT is carried out at 11-13 weeks in women considered to be at increased risk of GDM based on their demographic characteristics and medical history. Screening and diagnosis of GDM is traditionally delayed until the late second or early third trimester of pregnancy with the rationale that the diabetogenic effects of pregnancy increase with gestation and therefore delayed testing would maximize the detection rate.