Among the diabetic pregnant women the worst pregnancy outcome is seen in the subgroup of women with diabetic nephropathy. Development of signs of severe preeclampsia very early in pregnancy leading to very early preterm delivery is frequent.  The study of pathophysiologic mechanisms for the development of preeclampsia is covered and observational studies supporting the beneficial of antihypertensive treatment to pregnant women with microalbuminuria or diabetic nephropathy in preventing preeclampsia and early preterm delivery are presented. 

Aiming for strict glycemic control to prevent preterm delivery, the cornerstone is treatment with diet and insulin, but this treatment is associated with a high prevalence of severe hypoglycemia. Pathophysiological mechanisms of the increased risk of hypoglycaemia during pregnancy are explored and studies evaluating the use of insulin analogues, insulin pumps and continuous glucose monitoring to improve pregnancy outcome and reduce the risk of severe hypoglycaemia in pregnant women with type 1 diabetes are reported.

In addition to strict glycaemic control other factors involved in fetal overgrowth are explored and restricting maternal gestational weight gain is a promising candidate. The optimal carbohydrate content in the diet is discussed.

In summary, the lessons learned from this clinical research are that, both glycemic control, gestational weight gain and antihypertensive treatment are of importance for improving pregnancy outcome in pregnant women with pre-existing diabetes.  An example of using the app–technology for sharing the recent evidence based clinical recommendations to pregnant diabetic women or those planning pregnancy are given.