Neonatal diabetes mellitus, which may be transient or permanent, is rare. Most patients are full-term but small-for-gestational age.Typical symptoms of diabetes mellitus occur within the first 6 weeks of life, requiring insulin therapy and very strict blood glucose monitoring. Subsequent growth and psychomotor development are usually normal. In about 42% of these patients the diabetes remains permanent, the transient cases, however, often develop permanent diabetes mellitus later in life. Exocrine pancreatic insufficiency is present in some patients. Neonatal diabetes differs from type 1 diabetes in many aspects and seems to form a distinct entity of inborn pancreatic malfunction.