This unique book is a practical guide for the clinician faced with the challenge of diagnosing and managing neonates, infants and children with congenital hyperinsulinism (HI), within the framework of pathophysiology and molecular genetics. Major advances have been made in HI research over the past two decades, and with this better understanding of the molecular genetics of HI, a personalized approach to management according to the type of hyperinsulinism, and particularly according to the likelihood of focal hyperinsulinism, is starting to emerge. The opening chapter discusses HI diagnosis using biochemical approaches and phenotype characterization. The various forms of HI are then presented in detail in three main categories: diazoxide-responsive, diazoxide-unresponsive and syndromic HI. Both medical and surgical management strategies are then discussed, covering imaging, histology, surgical approach, and post-operative management.