The Molecular Basis of Neonatal Diabetes Mellitus and Transient Hyperglycemia in the Neonate

Neonatal diabetes mellitus (NDM) is a rare monogenic disorder characterized by persistent hyperglycemia requiring insulin therapy, typically diagnosed within the first six months of life, and may be transient οr permanent. However, hyperglycemia in the neonatal population may be observed outside the NDM range. This narrative review aims to provide an overview of the genetic and molecular mechanisms underlying NDM, including both transient and permanent forms on the one hand and the developmental and regulatory pathways contributing to transient hyperglycemic states in neonates on the other. A comprehensive literature search of PubMed, Scopus, and Google Scholar was conducted, focusing on genetic and molecular mechanisms associated with NDM and transient neonatal hyperglycemia. Mutations in more than 40 genes or chromosomal loci have been implicated in the pathogenesis of NDM, affecting the development and function of pancreatic beta-cells, as well as insulin synthesis and secretion. Abnormalities of the 6q24 locus have been recognized as the most common cause of transient NDM, whereas mutations in genes encoding ATP-sensitive potassium (KATP) channels, particularly KCNJ11, are more commonly identified in permanent NDΜ cases. Transient hyperglycemia may occur in preterm and/or critically ill neonates due to immaturity and transient beta-cell dysregulation, insulin resistance, epigenetic modifications, or drug administration. In NDM cases, the clinical course, the presence of extra-pancreatic manifestations, and the optimal treatment depend on the causative gene. Therefore, genetic diagnosis is imperative, as it can facilitate individualized management strategies, long-term follow-up, and genetic counselling.