title: Presentation, diagnostic features and glucose handling in a monocentric series of insulinomas.
abstract: BACKGROUND
  New aspects have emerged in the clinical and diagnostic scenarios of insulinoma: current guidelines have lowered the diagnostic insulin threshold to 3 μU/ml in the presence of hypoglycemia (<55 mg/dl); post-prandial hypoglycemia has been reported as the only presenting symptom; preexisting diabetes mellitus (DM) was recognized in some patients.
  
  
  OBJECTIVE
  To evaluate clinical features, diagnostic criteria and glucose metabolic profile in a monocentric series of patients affected by insulinomas including two subgroups: sporadic and multiple endocrine neoplasia type-1 syndrome (MEN-1).
  
  
  METHODS
  Clinical, pathological and biochemical data regarding 33 patients were analyzed.
  
  
  RESULTS
  following the current guidelines the 72-h fasting test was initially positive in all cases but one. In this case the test, initially negative, became positive after a 2-yr follow-up. Nadir insulin level was ≥ 3 μU/ml but <6 μU/ml in 3 patients and ≥ 6 μU/ml in the remaining 30 cases. At presentation, 27 patients (82%) reported only fasting symptoms, 3 (9%) only post-prandial and 3 (9%) both. Seven cases (21%) had previously been affected by type 2 DM or impaired glucose metabolism.
  
  
  CONCLUSIONS
  In our series the new cut-off of insulin increased the sensitivity of the 72-h fasting test from 87% to 97%. The absence of hypoglycemia during the test cannot definitively rule out the diagnosis and the test should be repeated in every highly suspicious case. Post-prandial hypoglycemia can be the only presenting symptom. DM may be associated with the occurrence of insulinoma. So that a possible diagnosis of insulinoma must not be ignored if previous impaired glucose handling is evident.
authors.affiliation: Department of Internal Medicine D, "G.B. Rossi" University Hospital, Verona, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Toaiari
authors.forename: M V
authors.initials: MV
authors.lastname: Davì
authors.forename: L
authors.initials: L
authors.lastname: Dalle Carbonare
authors.forename: L
authors.initials: L
authors.lastname: Boninsegna
authors.forename: C
authors.initials: C
authors.lastname: Castellani
authors.forename: M
authors.initials: M
authors.lastname: Falconi
authors.forename: G
authors.initials: G
authors.lastname: Francia
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001786:Blood Glucose / Q000378:metabolism; D003924:Diabetes Mellitus, Type 2 / Q000150:complications; D005215:Fasting / Q000009:adverse effects; D005260:Female; D005951:Glucose Tolerance Test; D006801:Humans; D007003:Hypoglycemia / Q000150:complications / Q000175:diagnosis; D007328:Insulin / Q000097:blood; D007340:Insulinoma / Q000097:blood / Q000150:complications / Q000175:diagnosis* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D018761:Multiple Endocrine Neoplasia Type 1 / Q000097:blood / Q000150:complications / Q000175:diagnosis; D010190:Pancreatic Neoplasms / Q000097:blood / Q000150:complications / Q000175:diagnosis* / Q000473:pathology; D019518:Postprandial Period; D012189:Retrospective Studies
chemical_list: D001786:Blood Glucose; D007328:Insulin