A majority of patients had a clear genetic etiology in which their PNDM was part of autosomal recessive syndromes or rare disorders due to abnormal early pancreatic development, including Wolcott–Rallison Syndrome (WRS), Fanconi–Bickel syndrome (FBS), and pancreatic agenesis due to PTF1A enhancer deletion, respectively. This evidence concerns the gene PTF1A and glycogen storage disease due to GLUT2 deficiency.