The prevalence of gestational diabetes mellitus (GDM) is increasing as the pregnant population becomes older and more obese. Fifteen percent of GDM patients require medical intervention. Insulin is still the drug of choice because it has not been implicated as a teratogen in human pregnancies.Insulin has its disadvantages such as the need for injections, the risk of hypoglycaemia, excessive weight gain and the costs. The use of oral anti hyperglicemic agent (OAHA), traditionally contraindicated, now can be considered as an alternative for insulin which can be beneficial in developing countries. From four groups of OAHA, sulfonylurea and biguanides can be used during pregnancy. Studies and randomized controlled trial (RCT) have been done and most summarized that it does not increase any maternal and perinatal morbidity. Most data also show that thereare also no differences in glycemic control or pregnancy outcomes compared with insulin. There are conflicting data shows metformin increase prevalence of preeclampsia patient and perinatal morbidity. OAHA USAge, although not yet recommended Internationally, can be considered in GDMpatients with uncontrolled blood sugar levels that require medical intervention but can not use insulin. Wellconducted, prospective, controlled studies regarding itsfeasibility in pregnant women with diabetes are still needed.