Criteria for diagnosis:
(1) multiple episodes of spontaneous hypoglycemia
(2) extremely high insulin levels with elevated C-peptide levels
(3) circulating anti-insulin (possibly anti-insulin receptor) antibodies
(4) no exposure to exogenous insulin
(5) exclusion of other causes
The elevated serum insulin level is partially an artifact of the anti-insulin antibodies, which may interfere with some immunoassays.
Biopsy of the pancreas may show nesidioblastosis, with diffuse hypertrophy and/or hyperplasia of islet cells.
Causes:
(1) drug-induced insulin antibodies following exposure to:
(1a) methimazole
(1b) alpha-mercaptopropionyl glycine
(1c) glutathione
(1d) possibly antibiotics
(2) autoimmune disease (Grave's disease, etc.)
Differential diagnosis:
(1) factitious hypoglycemia following self-injection of insulin
(2) insulin alloantibodies in a patient with diabetes mellitus
(3) insulinoma
