title: Whole-body insulin sensitivity rather than body-mass-index determines fasting and post-glucose-load growth hormone concentrations.
abstract: BACKGROUND
  Obese, non-acromegalic persons show lower growth hormone (GH) concentrations at fasting and reduced GH nadir during an oral glucose tolerance test (OGTT). However, this finding has never been studied with regard to whole-body insulin-sensitivity as a possible regulator.
  
  
  METHODS
  In this retrospective analysis, non-acromegalic (NonACRO, n = 161) and acromegalic (ACRO, n = 35), non-diabetic subjects were subdivided into insulin-sensitive (IS) and -resistant (IR) groups according to the Clamp-like Index (CLIX)-threshold of 5 mg · kg(-1) · min(-1) from the OGTT.
  
  
  RESULTS
  Non-acromegalic IS (CLIX: 8.8 ± 0.4 mg · kg(-1) · min(-1)) persons with similar age and sex distribution, but lower (p < 0.001) body-mass-index (BMI = 25 ± 0 kg/m2, 84% females, 56 ± 1 years) had 59% and 70%, respectively, higher (p < 0.03) fasting GH and OGTT GH area under the curve concentrations than IR (CLIX: 3.5 ± 0.1 mg · kg(-1) · min(-1), p < 0.001) subjects (BMI = 29 ± 1 kg/m2, 73% females, 58 ± 1 years). When comparing on average overweight non-acromegalic IS and IR with similar anthropometry (IS: BMI: 27 ± 0 kg/m2, 82% females, 58 ± 2 years; IR: BMI: 27 ± 0 kg/m2, 71% females, 60 ± 1 years), but different CLIX (IS: 8.7 ± 0.9 vs. IR: 3.8 ± 0.1 mg · kg(-1) · min(-1), p < 0.001), the results remained almost the same. In addition, when adjusted for OGTT-mediated glucose rise, GH fall was less pronounced in IR. In contrast, in acromegalic subjects, no difference was found between IS and IR patients with regard to fasting and post-glucose-load GH concentrations.
  
  
  CONCLUSIONS
  Circulating GH concentrations at fasting and during the OGTT are lower in non-acromegalic insulin-resistant subjects. This study seems the first to demonstrate that insulin sensitivity rather than body-mass modulates fasting and post-glucose-load GH concentrations in non-diabetic non-acromegalic subjects.
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine III, Medical University of Vienna, Vienna, Austria; Metabolic Unit, Institute of Biomedical Engineering, National Research Council (ISIB-CNR), Padua, Italy; Mariahilf Community Pharmacy, Arnoldstein, Austria; Medical Direction, Specialized Hospital Complex Agathenhof, Micheldorf, Austria.
authors.forename: Christian-Heinz
authors.initials: CH
authors.lastname: Anderwald
authors.affiliation: Metabolic Unit, Institute of Biomedical Engineering, National Research Council (ISIB-CNR), Padua, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Tura
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine III, Medical University of Vienna, Vienna, Austria.
authors.forename: Alois
authors.initials: A
authors.lastname: Gessl
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine III, Medical University of Vienna, Vienna, Austria.
authors.forename: Sabina
authors.initials: S
authors.lastname: Smajis
authors.affiliation: Clinical Institute of Medical and Chemical Laboratory Diagnostics, Medical University of Vienna, Vienna, Austria.
authors.forename: Christian
authors.initials: C
authors.lastname: Bieglmayer
authors.affiliation: Clinical Institute of Medical and Chemical Laboratory Diagnostics, Medical University of Vienna, Vienna, Austria.
authors.forename: Rodrig
authors.initials: R
authors.lastname: Marculescu
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine III, Medical University of Vienna, Vienna, Austria.
authors.forename: Anton
authors.initials: A
authors.lastname: Luger
authors.affiliation: Metabolic Unit, Institute of Biomedical Engineering, National Research Council (ISIB-CNR), Padua, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Pacini
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine III, Medical University of Vienna, Vienna, Austria.
authors.forename: Michael
authors.initials: M
authors.lastname: Krebs
mesh_terms: D000172:Acromegaly / Q000503:physiopathology*; D000886:Anthropometry; D001786:Blood Glucose / Q000032:analysis*; D015992:Body Mass Index; D005215:Fasting / Q000502:physiology*; D005260:Female; D005500:Follow-Up Studies; D005951:Glucose Tolerance Test; D019382:Human Growth Hormone / Q000378:metabolism*; D006801:Humans; D007333:Insulin Resistance; D008297:Male; D008875:Middle Aged; D009765:Obesity; D011379:Prognosis; D012189:Retrospective Studies
chemical_list: D001786:Blood Glucose; D019382:Human Growth Hormone