Non-autoimmune acute-onset type 1 diabetes mellitus newly developed in an elderly patient presenting elevation of serum pancreatic exocrine enzymes.

An 82 year-old female patient not suffering from diabetes was transported to our hospital with hyperglycemia (HbA1c 8.2%, blood glucose 584 mg/dL) and mildly increased levels of pancreatic exocrine enzymes (amylase 543 IU/L, lipase 59 U/L, elastase-1 479 ng/dL), while there were no findings indicating pancreatitis. Under a diagnosis of new-onset diabetes, she was discharged with oral hypoglycemic agents, as retention of insulin secretion function [blood glucose 117 mg/dL, serum connecting peptide immunoreactivity (CPR) 1.63 ng/mL] with normalization of the enzymes was confirmed following administration. However, at 73 days after the hospitalization, she returned with diabetic ketoacidosis (blood glucose 910 mg/dL, pH in blood gas analysis 7.15, total blood ketone bodies > 7000 µmol/L) with a transient repeated increase of the enzymes (amylase 382 IU/L, lipase 82 U/L, elastase-1 569 ng/dL) and without pancreatitis. Notably, depletion of insulin secretion (6.1 µg/day in urine, 0.36 ng/mL in serum CPR with no response in glucagon-loading test) was revealed, and serum CPR level remained low after discharge. Together with negative findings for islet-related autoantibodies, the patient was diagnosed with acute-onset type 1B diabetes (T1BD). In the present patient with acute-onset T1BD, a mild increase in pancreatic exocrine enzymes was repeatedly observed, which may mimic fulminant type and raise questions for us about the commonly accepted pathophysiology of T1D. These findings may help to clarify issues related to newly developed T1D in elderly individuals. © The Japan Diabetes Society 2021, corrected publication 2021.