The prevalence of both obesity and gestational diabetes mellitus (GDM) is rising worldwide. The complications of diabetes affecting the mother and fetus are well known. Maternal complications include preterm labor, pre-eclampsia, nephropathy, birth trauma, cesarean section, and postoperative wound complications, among others. Fetal complications include fetal wastage from early pregnancy loss or congenital anomalies, macrosomia, shoulder dystocia, stillbirth, growth restriction, and hypoglycemia, among others. The presence of obesity among diabetic patients compounds these complications. The above-mentioned short-term complications can be mediated by achieving the desired level of glycemic control during pregnancy. However, GDM during pregnancy is associated with increased risk of early obesity, type 2 diabetes during adolescence and the development of metabolic syndrome in early childhood. Additionally, GDM is a marker for the development of overt type 2 diabetes and metabolic syndrome for the mother in the early future.