Neonatal diabetes mellitus (NDM) is a rare disease reported to have an incidence of one in 400,000 to 500,000 live births. The disorder may be more common as it is not routinely considered a diagnostic possibility by many neonatologists who may routinely use insulin to treat neonatal hyperglycemia. NDM can be grouped into two distinct clinical entities--transient and permanent--based on certain features detailed herein; however, distinction between the two categories can only be definitely made in hindsight. Treatment is with insulin; however, determining the correct dose and method of delivery is often challenging, given the sensitivity of neonates to insulin and the risk of hypoglycemia. We report the successful use of Glargine insulin in the treatment of three infants with NDM, review the recent discoveries, and discuss guidelines for the care of newborns with NDM.