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.