Objective: The management of pregnant women with diabetes mellitus places a significant burden on healthcare systems. Significant global changes have been proposed with regard to the diagnosis and management of women with diabetes mellitus in pregnancy. The study aims were to document the contemporary numbers, treatments and outcomes of diabetes mellitus in pregnancy, with particular focus on gestational and type 2 diabetes mellitus.Design, subjects and setting: A retrospective audit was performed of pregnant women (n = 278) with diabetes mellitus, managed over a 12-month period in a combined secondary and tertiary unit in South Africa.Results: Of the 278 cases analysed, 60% had gestational and 33% type 2 diabetes mellitus. The perinatal mortality ratio for all diabetes mellitus in pregnancy was 52.6:1 000, with only one early neonatal death. Ninety-five per cent and 70% of women with gestational and type 2 diabetes mellitus, respectively, were overweight or obese. Chronic hypertension was present in 23% of women with gestational and in 42% of women with type 2 diabetes mellitus. The glycosylated haemoglobin decreased from 6.7% at diagnosis to 6.4% at delivery in the gestational diabetes mellitus group, and from 7.5% at booking to 6.6% at delivery in the type 2 diabetes mellitus subjects. Lifestyle modification and metformin sufficed in 88% of women with gestational diabetes mellitus. Insulin was only required in 12% of pregnancies with gestational and in 53% of pregnancies with type 2 diabetes mellitus.Conclusion: Pregnancies complicated by gestational and type 2 diabetes mellitus are common and challenging. The addition of the oral agent, metformin, lowers the need for insulin therapy.Keywords: diabetes mellitus, glucose threshold, maternal and foetal health, pregnanc