Hyperinsulinaemic hypoglycemia associated with ectopic Cushing syndromes due to a pancreatic endocrine tumor in a type 2 diabetes mellitus patient: clinical implications of a rare association.
Background: The coexistence of insulin and ACTH hypersecretion in the same
patient is extremely rare. A diabetic patient with a pancreatic endocrine tumor
(PET) co-secreting insulin and ACTH is still more rare and has never been
described. The combination of these two endocrine syndromes results in a peculiar
clinical picture. Aim: To determine the cause of glycemic variations in a patient
with previously stable diabetes mellitus. Subjects and Methods: This is a
clinical case report from the Endocrinology Unit of Aosta Hospital and Internal
Medicine and Surgical Unit of Verona University. A 69 year-old diabetic patient
was hospitalized for recurrent severe hypoglycemic events persistent after
withdrawal of anti-diabetic drugs. The causes of hypoglycemia and subsequent
resumption of hyperglycemia were investigated. Results: An insulin secreting PET
was diagnosed. Diazoxide and octreotide therapy initially was able to control
hypoglycemic symptoms, then, a Cushing's syndrome occurred resulting in worsening
of diabetes control. ACTH was found to be released by the PET previously
diagnosed as an insulin secreting tumor. The tumor was removed and the histology
was consistent with a well differentiated endocrine carcinoma. After surgery,
adrenal function was normal and insulin therapy was newly necessary to control
diabetes. Conclusions: A single PET may be responsible for both a
hyperinsulinaemic and a Cushing's syndrome. When this rare association occurs,
each of the two syndromes may affect the other resulting in a peculiar clinical
course. Finally, an insulin secreting PET has to be kept in mind as a rare cause
of hypoglycemia in diabetic patients
