Gestational diabetes mellitus (GDM) is defined as diabetes diagnosed during pregnancy that is not clearly overt diabetes. The current diagnostic criteria are as per recommendations of International Association of Diabetes in Pregnancy Study Groups (IADPSG) and is based on Hyperglycaemia and Adverse Pregnancy Outcome (HAPO) study. Gestational diabetes has implications both for foetus and mother, and diagnosis and treatment of GDM improves pregnancy outcome. The first line of management of women with gestational diabetes consists of medical nutrition therapy (MNT) with adjunctive exercise. Oral hypoglycaemic agents (metformin, glyburide) have been found safe in pregnancy. Insulin is considered the standard for management of GDM. Self monitoring of blood glucose has been associated with a number of maternal and foetal benefits. Maintenance of euglycaemia is important in intra-partum period also to prevent neonatal hypoglycaemia. GDM is associated with increased long-term risks of diabetes, metabolic syndrome and increased cardiovascular disorders both in mother as well as in offspring. Women with apparent diabetes and impaired glucose tolerance should be identified by postpartum screening.