Diabetes mellitus and profound insulin resistance in Johanson-Blizzard syndrome.

: Pancreatic exocrine insufficiency in Johanson-Blizzard syndrome (JBS) is well described but only two previous patient reports document pancreatic endocrine insufficiency manifested as diabetes mellitus, and each patient required only a modest dose of insulin to control hyperglycemia. We report a patient with JBS and new-onset diabetes mellitus with profound insulin resistance, with no clinical or laboratory evidence of pancreatic exocrine insufficiency.