title: Studies of insulin resistance in patients with clinical and subclinical hyperthyroidism.
abstract: OBJECTIVE
  Although clinical hyperthyroidism (HR) is associated with insulin resistance, the information on insulin action in subclinical hyperthyroidism (SHR) is limited.
  
  
  METHODS
  To investigate this, we assessed the sensitivity of glucose metabolism to insulin in vivo (by an oral glucose tolerance test) and in vitro (by measuring insulin-stimulated rates of glucose transport in isolated monocytes) in 12 euthyroid subjects (EU), 16 patients with HR, and 10 patients with SHR.
  
  
  RESULTS
  HR and SHR patients displayed higher postprandial glucose levels (area under the curve, AUC(0)(-)(300) 32,190±1067 and 31,497±716,mg/dl min respectively) versus EU (27,119±1156 mg/dl min, P<0.05). HR but not SHR patients displayed higher postprandial insulin levels (AUC(0)(-)(300) 11,020±985 and 9565±904 mU/l min respectively) compared with EU subjects (AUC(0)(-)(300) 7588±743 mU/l min, P<0.05). Homeostasis model assessment index was increased in HR and SHR patients (2.81±0.3 and 2.43±0.38 respectively) compared with EU subjects (1.27±0.16, P<0.05), while Matsuda and Belfiore indices were decreased in HR (4.21±0.41 and 0.77±0.05 respectively, P<0.001) and SHR patients (4.47±0.33 and 0.85±0.05 respectively, P<0.05 versus EU (7.76±0.87 and 1 respectively). At 100 μU/ml insulin, i) GLUT3 levels on the monocyte plasma membrane were increased in HR (468.8±7 mean fluorescence intensity (MFI)) and SHR patients (522.2±25 MFI) compared with EU subjects (407±18 MFI, P<0.01 and P<0.05 respectively), ii) glucose transport rates in monocytes (increases from baseline) were decreased in HR patients (37.8±5%) versus EU subjects (61.26±10%, P<0.05).
  
  
  CONCLUSIONS
  Insulin-stimulated glucose transport in isolated monocytes of patients with HR was decreased compared with EU subjects. Insulin resistance was comparable in patients with both HR and SHR.
authors.affiliation: Hellenic National Center for Research, Prevention and Treatment of Diabetes Mellitus and its Complications (HNDC), Athens, Greece.
authors.forename: Eirini
authors.initials: E
authors.lastname: Maratou
authors.forename: Dimitrios J
authors.initials: DJ
authors.lastname: Hadjidakis
authors.forename: Melpomeni
authors.initials: M
authors.lastname: Peppa
authors.forename: Maria
authors.initials: M
authors.lastname: Alevizaki
authors.forename: Katerina
authors.initials: K
authors.lastname: Tsegka
authors.forename: Vaia
authors.initials: V
authors.lastname: Lambadiari
authors.forename: Panayota
authors.initials: P
authors.lastname: Mitrou
authors.forename: Eleni
authors.initials: E
authors.lastname: Boutati
authors.forename: Anastasios
authors.initials: A
authors.lastname: Kollias
authors.forename: Theofanis
authors.initials: T
authors.lastname: Economopoulos
authors.forename: Sotirios A
authors.initials: SA
authors.lastname: Raptis
authors.forename: George
authors.initials: G
authors.lastname: Dimitriadis
mesh_terms: D000328:Adult; D001692:Biological Transport / Q000187:drug effects; D002478:Cells, Cultured; D005260:Female; D005947:Glucose / Q000378:metabolism; D005951:Glucose Tolerance Test; D006801:Humans; D006980:Hyperthyroidism / Q000097:blood / Q000503:physiopathology*; D007328:Insulin / Q000097:blood / Q000494:pharmacology; D007333:Insulin Resistance / Q000502:physiology*; D008297:Male; D008875:Middle Aged
chemical_list: D007328:Insulin; D005947:Glucose