title: Effect of 2 years of testosterone replacement on insulin secretion, insulin action, glucose effectiveness, hepatic insulin clearance, and postprandial glucose turnover in elderly men.
abstract: OBJECTIVE
  We sought to determine whether, and if so the mechanism by which, testosterone replacement improves carbohydrate tolerance.
  
  
  METHODS
  Fifty-five elderly men with relative testosterone deficiency ingested a labeled mixed meal and underwent a frequently sampled labeled intravenous glucose tolerance test before and after either placebo or treatment with testosterone patch (5 mg/day) for 2 years.
  
  
  RESULTS
  Despite restoring bioavailable testosterone to values observed in young men, the change (24 months minus baseline values) in fasting and postprandial glucose, insulin, and C-peptide concentrations and meal appearance, glucose disposal, and endogenous glucose production were virtually identical to those observed after 2 years of placebo. The change over time in insulin and C-peptide concentrations post-intravenous glucose injection also did not differ. Furthermore, the change over time in insulin action and glucose effectiveness (measured with the unlabeled and labeled "oral" and "intravenous" minimal models), as well as insulin secretion and hepatic insulin clearance (measured with the C-peptide model), did not differ in the testosterone and placebo groups.
  
  
  CONCLUSIONS
  We conclude that 2 years of treatment with testosterone in elderly men does not improve carbohydrate tolerance or alter insulin secretion, insulin action, glucose effectiveness, hepatic insulin clearance, or the pattern of postprandial glucose metabolism. Thus, testosterone deficiency is unlikely the cause of the age-associated deterioration in glucose tolerance commonly observed in elderly men.
authors.affiliation: Division of Endocrinology, Diabetes, Metabolism and Nutrition, Mayo Clinic College of Medicine, Rochester, MN 55905, USA.
authors.forename: Rita
authors.initials: R
authors.lastname: Basu
authors.forename: Chiara
authors.initials: C
authors.lastname: Dalla Man
authors.forename: Marco
authors.initials: M
authors.lastname: Campioni
authors.forename: Ananda
authors.initials: A
authors.lastname: Basu
authors.forename: K Sreekumaran
authors.initials: KS
authors.lastname: Nair
authors.forename: Michael D
authors.initials: MD
authors.lastname: Jensen
authors.forename: Sundeep
authors.initials: S
authors.lastname: Khosla
authors.forename: George
authors.initials: G
authors.lastname: Klee
authors.forename: Gianna
authors.initials: G
authors.lastname: Toffolo
authors.forename: Claudio
authors.initials: C
authors.lastname: Cobelli
authors.forename: Robert A
authors.initials: RA
authors.lastname: Rizza
mesh_terms: D000279:Administration, Cutaneous; D000368:Aged; D001786:Blood Glucose / Q000187:drug effects / Q000378:metabolism*; D001823:Body Composition; D002096:C-Peptide / Q000097:blood; D004311:Double-Blind Method; D006019:Glycolysis / Q000187:drug effects; D006801:Humans; D007328:Insulin / Q000097:blood / Q000378:metabolism*; D000078790:Insulin Secretion; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D010919:Placebos; D019518:Postprandial Period; D013739:Testosterone / Q000008:administration & dosage / Q000097:blood / Q000172:deficiency / Q000627:therapeutic use*
chemical_list: D001786:Blood Glucose; D002096:C-Peptide; D007328:Insulin; D010919:Placebos; D013739:Testosterone