Neonatal diabetes mellitus (NDM) is a rare kind of diabetes characterized by hyperglycemia and low levels of insulin. Clinically, it is categorized into two main types: transient NDM (TNDM) and permanent NDM (PNDM). These types are diagnosed based on duration of insulin dependence early in the disease. In TNDM, diabetes begins in the first few weeks of life with remission in a few months. However, infant with PNDM have insulin secretory failure in the late fetal or early post-natal period with no remission. Mutation in the KCNJ11 and ABCC8 genes can cause both TNDM and PNDM, and infant with this mutation can respond to transition from insulin to sulfonylureas making identification of genes involved in the disease important for appropriate treatment.