In 1989 the St. Vincent Declaration aimed to achieve comparable pregnancy outcomes in women with diabetes and those with normal glucose tolerance. However, currently women with pre-gestational diabetes still feature a higher risk of perinatal morbidity and even increased mortality. This fact is mostly ascribed to a persistently low rate of pregnancy planning and pre-pregnancy care with optimization of metabolic control prior to conception. All women should be experienced in the management of their therapy and on stable glycemic control prior to conception. In addition, thyroid dysfunction, hypertension as well as the presence of diabetic complications should be excluded or treated adequately before pregnancy in order to decrease the risk for a progression of complications during pregnancy as well as maternal and fetal morbidity. Near normoglycaemia and HbA in the normal range are targets for treatment, preferably without the induction of frequent resp. severe hypoglycaemic reactions. Especially in women with type 1 diabetes mellitus the risk of hypoglycemia is high in early pregnancy, but it decreases with the progression of pregnancy due to hormonal changes causing an increase of insulin resistance. In addition, obesity increases worldwide and contributes to higher numbers of women at childbearing age with type 2 diabetes mellitus and adverse pregnancy outcomes. Intensified insulin therapy with multiple daily insulin injections and pump treatment are equally effective in reaching good metabolic control during pregnancy. Insulin is the primary treatment option. Continuous glucose monitoring often adds to achieve targets. Oral glucose lowering drugs (Metformin) may be considered in obese women with type 2 diabetes mellitus to increase insulin sensitivity but need to be prescribed cautiously due to crossing the placenta and lack of long-time follow up data of the offspring (shared decision making). Due to increased risk for preeclampsia in women with diabetes screening needs to be performed. Regular obstetric care as well as an interdisciplinary treatment approach are necessary to improve metabolic control and ensure the healthy development of the offspring.