A case of slowly progressive insulin-dependent diabetes mellitus in which the patient developed diabetic ketoacidosis resembling the onset of fulminant type 1 diabetes mellitus

A 65-year-old man first visited our hospital in 1987 at 41 years of age. At that time, he was diagnosed with non-insulin dependent diabetes mellitus and prescribed a sulfonylurea. In 1996, he was admitted to our hospital due to poor glycemic control, with a urinary CPR level of 52 μg/day. In 2007, he was found to be GAD antibody-positive and diagnosed with SPIDDM. The urinary CPR level subsequently declined to 23.6 μg/day, and the insulin regimen was changed to intensive insulin therapy. In November 2012, he was found lying on the floor unconscious and taken to our ER. On admission, his plasma glucose level was 861 mg/dl, his HbA1c level was 7.5 %, his blood pH was 6.99 and he was positive for urinary ketone bodies; therefore, he was diagnosed with diabetic ketoacidosis (DKA). He had developed DKA within one week, with a relatively low degree of HbA1c elevation compared to the plasma glucose level. His endogenous insulin secretion was exhausted, which fulfilled the diagnostic criteria for fulminant type 1 diabetes mellitus. Moreover, the exocrine pancreatic enzyme levels were elevated, and he had experienced preceding gastrointestinal symptoms prior to the onset of DKA. We herein described a rare case of SPIDDM with DKA in which the patient was also diagnosed with fulminant type 1 diabetes mellitus.