title: Acute lysine supplementation does not improve hepatic or peripheral insulin sensitivity in older, overweight individuals.
abstract: BACKGROUND
  Lysine supplementation may have a positive influence on the regulation of glucose metabolism but it has not been tested in the geriatric population.
  
  
  OBJECTIVE
  We evaluated the impact of acute lysine supplementation using three randomized experimental scenarios: 1) oral glucose alone (control), 2) oral glucose and low-dose lysine (2 grams), and oral glucose and high dose lysine (5 grams) lysine in 7 older (66 ± 1 years/age), overweight/obese (BMI = 28 ± 2 kg/m(2)) individuals.
  
  
  METHODS
  We utilized a dual tracer technique (i.e., [6,6-(2)H2] glucose primed constant infusion and 1-[(13)C] glucose oral ingestion) during an oral glucose tolerance test (OGTT) to examine differences in hepatic and peripheral insulin sensitivity under all three scenarios.
  
  
  RESULTS
  Post-absorptive plasma glucose and insulin concentrations were not different between the three trials. Similarly, the response of glucose and insulin concentrations during the oral glucose tolerance tests (OGTT) was similar in the three trials. The results of the Matsuda index (ISI/M) were also not different between the three trials. As an index of hepatic insulin sensitivity, there were no significant differences in the endogenous glucose rate of appearance (glucose Ra) for control, 2 g lysine and 5 g lysine (1.2 ± 0.1, 1.1 ± 0.1, 1.3 ± 0.1 mg•kg(-1)•min(-1)), respectively. With respect to peripheral insulin sensitivity, there were no significant differences in the glucose rate of disappearance (glucose Rd) for control, 2 g lysine and 5 g lysine (4.2 ± 0.1, 4.3 ± 0.2, and 4.5 ± 0.4 mg•kg(-1)•min(-1)), respectively.
  
  
  CONCLUSIONS
  Previous studies in younger participants have suggested that lysine may have a beneficial effect on glucose metabolism. However, acute lysine supplementation in the older population does not facilitate beneficial changes in glucose Ra or glucose Rd.
authors.affiliation: Center for Translational Research in Aging and Longevity, Reynolds Institute on Aging, University of Arkansas for Medical Sciences, Little Rock, AR USA.
authors.forename: Il-Young
authors.initials: IY
authors.lastname: Kim
authors.affiliation: Center for Translational Research in Aging and Longevity, Reynolds Institute on Aging, University of Arkansas for Medical Sciences, Little Rock, AR USA.
authors.forename: Rick H
authors.initials: RH
authors.lastname: Williams
authors.affiliation: Center for Translational Research in Aging and Longevity, Reynolds Institute on Aging, University of Arkansas for Medical Sciences, Little Rock, AR USA.
authors.forename: Scott E
authors.initials: SE
authors.lastname: Schutzler
authors.affiliation: Center for Translational Research in Aging and Longevity, Reynolds Institute on Aging, University of Arkansas for Medical Sciences, Little Rock, AR USA.
authors.forename: Cosby J
authors.initials: CJ
authors.lastname: Lasley
authors.affiliation: Center for Translational Research in Aging and Longevity, Reynolds Institute on Aging, University of Arkansas for Medical Sciences, Little Rock, AR USA.
authors.forename: Donald L
authors.initials: DL
authors.lastname: Bodenner
authors.affiliation: Center for Translational Research in Aging and Longevity, Reynolds Institute on Aging, University of Arkansas for Medical Sciences, Little Rock, AR USA.
authors.forename: Robert R
authors.initials: RR
authors.lastname: Wolfe
authors.affiliation: Center for Alaska Native Health Research, Institute of Arctic Biology, University of Alaska-Fairbanks, 902 North Koyukuk Drive, Fairbanks, AK 99775-7000 USA.
authors.forename: Robert H
authors.initials: RH
authors.lastname: Coker
keywords: Insulin resistance; Liver; Muscle