title: Improvement of insulin resistance following transsphenoidal surgery in patients with acromegaly: correlation with serum IGF-I levels.
abstract: OBJECTIVE
  The aim of this study was to determine the correlation between the growth hormone (GH)-insulin-like growth factor-I (IGF-I) axis and glucose intolerance in acromegaly during the early postoperative period.
  
  
  METHODS
  The study included 20 patients with acromegaly caused by GH-secreting pituitary adenoma who received transsphenoidal surgery in our hospital. Glucose tolerance was evaluated with oral glucose tolerance tests (OGTTs) performed during pre- and early postoperative periods (9 [7-18] days after surgery). Homeostasis model assessment of insulin resistance (HOMA-IR) and insulinogenic index (IGI) were calculated, and correlation analyses were performed between these values and the GH-IGF-I axis. Patients were divided according to postoperative changes of the axis, and glucose tolerance was compared between the groups.
  
  
  RESULTS
  In preoperative OGTTs, nine patients had impaired glucose tolerance and two had diabetes mellitus patterns. Postoperatively, significant reduction was observed both in fasting plasma glucose levels (p<0.01) and in HOMA-IR (p<0.01), whereas IGI showed no significant change. HOMA-IR was significantly correlated with serum IGF-I levels both before (r=0.83, p<0.01) and after (r=0.57, p<0.01) surgery, although it was not correlated with serum GH levels. Patients who achieved more than 50% postoperative reduction in serum IGF-I levels showed significant improvement in OGTTs results (p<0.05).
  
  
  CONCLUSIONS
  In patients with acromegaly, serum IGF-I levels, but not GH levels, were significantly correlated with insulin resistance. Early postoperative improvement of glucose tolerance is observed in patients who achieved postoperative reduction in serum IGF-I levels.
authors.affiliation: Center for Diabetes and Endocrinology, The Tazuke Kofukai Foundation Medical Research Institute Kitano Hospital, Osaka, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Mori
authors.forename: Y
authors.initials: Y
authors.lastname: Iwasaki
authors.forename: Y
authors.initials: Y
authors.lastname: Kawasaki-Ogita
authors.forename: S
authors.initials: S
authors.lastname: Honjo
authors.forename: Y
authors.initials: Y
authors.lastname: Hamamoto
authors.forename: H
authors.initials: H
authors.lastname: Tatsuoka
authors.forename: K
authors.initials: K
authors.lastname: Fujimoto
authors.forename: H
authors.initials: H
authors.lastname: Ikeda
authors.forename: Y
authors.initials: Y
authors.lastname: Wada
authors.forename: Y
authors.initials: Y
authors.lastname: Takahashi
authors.forename: J
authors.initials: J
authors.lastname: Takahashi
authors.forename: H
authors.initials: H
authors.lastname: Koshiyama
mesh_terms: D000172:Acromegaly / Q000097:blood / Q000209:etiology / Q000601:surgery*; D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000097:blood*; D005260:Female; D005500:Follow-Up Studies; D019382:Human Growth Hormone / Q000097:blood; D006801:Humans; D007333:Insulin Resistance; D007334:Insulin-Like Growth Factor I / Q000032:analysis*; D008297:Male; D008875:Middle Aged; D019635:Neurosurgical Procedures; D010911:Pituitary Neoplasms / Q000097:blood / Q000150:complications; D011184:Postoperative Period; D011379:Prognosis; D013101:Sphenoid Sinus / Q000601:surgery*; D055815:Young Adult
chemical_list: D015415:Biomarkers; D019382:Human Growth Hormone; D007334:Insulin-Like Growth Factor I