Gestational diabetes, because of its not only high prevalence but also resulting complications in both mother and fetus makes it one of the most important problem of a pregnant woman. The exact cause of gestational diabetes is unknown. Obviously, there is no one reason for the development of the disease. Placental hormones likely play a role. Insulin resistance is in the center and some factors like adipokines, lipids, inflammation, oxidative stress, heavy metals, gut microbiota, autoimmunity, metabolomics, genetic factors and vitamin D are the determinants for the development of insulin resistance and disease itself. Worldwide distribution of the disease changes according to geography. Ethnic factors also play role. Although some well-known risk factors have role in the development of the disease, 1 in 20 women without any risk factors also develop GDM. There is no universal screening and diagnostic methods. Some countries use universal screening some others prefer selective screening of women with risk factors. In addition, some suggest use of one-step diagnosis, while others two-step. The most challenging issue is use of some biomarkers in early (first trimester) diagnosis of pregnancy to prevent development of GDM. Many modalities are used in treatment. Medical nutrition therapy is still the basis of management. Exercise has some roles, too. Besides pharmacotherapies like insulin and oral antidiabetics, some modern modalities like insulin pump therapy together with continuous glucose monitoring, telemedicine, dietary supplements like myoinositols are also covered in this book. Monitorization is important in diabetes and role of nurses in follow-up is incontrovertible. If not treated well, both fetus and mother are open to complications. From congenital malformations to macrosomia, if inevitable, proper management of these problems has to be considered. Some comorbidities like hypertension, thyroid problems and psychosocial stress complicate the problem further. Fetal monitorization, time and type of delivery and management of glycaemia during peripartum period are the issues to be considered towards to end of pregnancy. The problem does not finish with the birth of baby. Both mother and newborn has to be followed for the development of future problems like postpartum diabetes and obesity. Nutrition and benefits of breastfeeding are important points for the health of the baby. In addition, every efforts has to be spent to prevent recurrence of the disease in subsequent pregnancies. The most important instrument against fighting a disease is information i.e. how much we know about it. Understanding the problem thoroughly strengthens our hands to cope and overcome it more easily. The main target of this book is to handle every aspect of the disease from diagnosis to treatment as evident from the title. It is a candidate for a reference guide in this subject. It includes most recent and update data on gestational diabetes.