**1. Introduction**

Pregnancy is usually a joyous event for most women and their families in many cultures. However, in certain situations, this celebratory moment is marred by various maternal complications; chief among them is diabetes mellitus.

Diabetes mellitus, also known as diabetes, is a metabolic disorder characterised by high blood glucose levels over a long period of time [1]. In pregnant women, it manifests as either gestational diabetes mellitus (GDM) or pre-existing diabetes [2]. Gestational diabetes mellitus (GDM) is defined as glucose intolerance of variable degree that is first discovered during pregnancy [3], while pre-existing diabetes is glucose intolerance existing before pregnancy.

Diabetes in pregnancy is associated with a number of poor outcomes during the pregnancy period, during childbirth, and the immediate postpartum period [2]. Infants of mothers with pre-existing diabetes mellitus also experience double the risk of serious injury at birth, triple the likelihood of caesarean delivery and quadruple the incidence of new-born intensive care unit (NICU) admission [4].

In this chapter, we'll be exploring the prevalence of diabetes in pregnancy, the body's adaptation to pregnancy, the pathophysiology of diabetes in pregnancy, associated complications, diagnostic criteria for GDM and PDM, the management of this condition, and recommendations to reduce its prevalence.
