title: Desacyl ghrelin is influenced by changes in insulin concentration during an insulin tolerance test.
abstract: OBJECTIVE
  Ghrelin, a gut-brain peptide, regulates energy homeostasis and glucose metabolism and is present in acylated and nonacylated form in the circulation. Although desacyl ghrelin (DAG), the predominant form of ghrelin, is associated with insulin sensitivity and improved metabolic state, not much is known about its direct regulation by insulin. We aimed to assess changes in DAG in response to the rapid increase in insulin concentration during an insulin tolerance test (ITT) in normal weight and obese subjects.
  
  
  METHODS
  We performed an observational single center study. An ITT was assessed in eight subjects (four males), median age of 29.9 years (range 19.6-42.0). DAG concentrations were measured at 20, 40, 60 and 90 min after insulin infusion. Homeostatic Model Assessment (HOMA) was calculated from fasting insulin and glucose. Body mass index (BMI) and waist circumference were assessed.
  
  
  RESULTS
  Three subjects were obese (BMI ≥ 30 kg/m(2)), one subject was overweight (BMI = 25-30 kg/m(2)) and four subjects had normal weight (BMI = 18.5-25 kg/m(2)). Median DAG decreased after insulin infusion (90 pg/mL, p = 0.028), especially in normal weight subjects. Baseline DAG was lower in subjects with higher BMI (ρ = -0.76, p = 0.028) and higher fasting insulin (ρ = -0.76, p = 0.030). DAG changes correlated with fasting insulin levels (ρ = -0.85, p = 0.007), HOMA (ρ = -0.86, p = 0.007), BMI (ρ = -0.83, p = 0.010) and waist circumference (ρ = -0.93, p < 0.001).
  
  
  CONCLUSIONS
  DAG levels rapidly decreased in response to insulin administration in normal subjects, but not in insulin-resistant obese who are in a state of relative DAG deficiency.
authors.affiliation: Department of Medicine - section Endocrinology, Erasmus University Medical Center, P.O. Box 2040, 3000 CA Rotterdam, The Netherlands. k.blijdorp@erasmusmc.nl
authors.forename: K
authors.initials: K
authors.lastname: Blijdorp
authors.forename: A J
authors.initials: AJ
authors.lastname: van der Lely
authors.forename: M M
authors.initials: MM
authors.lastname: van den Heuvel-Eibrink
authors.forename: T M
authors.initials: TM
authors.lastname: Huisman
authors.forename: A P N
authors.initials: AP
authors.lastname: Themmen
authors.forename: P J D
authors.initials: PJ
authors.lastname: Delhanty
authors.forename: S J C M M
authors.initials: SJ
authors.lastname: Neggers
mesh_terms: D000328:Adult; D003940:Diagnostic Techniques, Endocrine; D004305:Dose-Response Relationship, Drug; D005215:Fasting; D005260:Female; D054439:Ghrelin / Q000097:blood*; D015309:Glucose Clamp Technique; D006801:Humans; D056865:Ideal Body Weight / Q000502:physiology; D007328:Insulin / Q000008:administration & dosage* / Q000097:blood*; D007333:Insulin Resistance; D008297:Male; D009765:Obesity / Q000097:blood; D050177:Overweight / Q000097:blood; D055815:Young Adult
chemical_list: D054439:Ghrelin; D007328:Insulin; C422650:ghrelin, des-n-octanoyl
keywords: Desacyl ghrelin; Insulin resistance; Insulin tolerance test; Obesity