The incidence of type 1 and type 2 diabetes amongst women of reproductive age is increasing worldwide. Despite recent advances in treatment options for diabetes outside of pregnancy, women still have a significantly increased risk of adverse obstetric outcomes including perinatal death and congenital malformation, compared to the non-diabetic population. An understanding of the physiological changes during pregnancy, management, early detection and prevention of complications and pre-pregnancy care, specific to women with pre-existing diabetes, is important in improving health outcomes in this growing group of women. This review particularly focuses on areas where there have been recent developments or controversy.