title: Inverse association between insulin resistance and gait speed in nondiabetic older men: results from the U.S. National Health and Nutrition Examination Survey (NHANES) 1999-2002.
abstract: BACKGROUND
  Recent studies have revealed the associations between insulin resistance (IR) and geriatric conditions such as frailty and cognitive impairment. However, little is known about the relation of IR to physical impairment and limitation in the aging process, eg. slow gait speed and poor muscle strength. The aim of this study is to determine the effect of IR in performance-based physical function, specifically gait speed and leg strength, among nondiabetic older adults.
  
  
  METHODS
  Cross-sectional data were from the population-based National Health and Nutrition Examination Survey (1999-2002). A total of 1168 nondiabetic adults (> or = 50 years) with nonmissing values in fasting measures of insulin and glucose, habitual gait speed (HGS), and leg strength were analyzed. IR was assessed by homeostasis model assessment (HOMA-IR), whereas HGS and peak leg strength by the 20-foot timed walk test and an isokinetic dynamometer, respectively. We used multiple linear regression to examine the association between IR and performance-based physical function.
  
  
  RESULTS
  IR was inversely associated with gait speed among the men. After adjusting demographics, body mass index, alcohol consumption, smoking status, chronic co-morbidities, and markers of nutrition and cardiovascular risk, each increment of 1 standard deviation in the HOMA-IR level was associated with a 0.04 m/sec decrease (p = 0.003) in the HGS in men. We did not find such association among the women. The IR-HGS association was not changed after further adjustment of leg strength. Last, HOMA-IR was not demonstrated in association with peak leg strength.
  
  
  CONCLUSIONS
  IR is inversely associated with HGS among older men without diabetes. The results suggest that IR, an important indicator of gait function among men, could be further investigated as an intervenable target to prevent walking limitation.
authors.affiliation: Department of Emergency Medicine, Chang-Gung Memorial Hospital-Kaohsiung Medical Center, No.123, Dapi Rd., NiaosongTownship, Kaohsiung County 833, Taiwan. chenkokuo@yahoo.com.tw
authors.forename: Chen-Ko
authors.initials: CK
authors.lastname: Kuo
authors.forename: Lian-Yu
authors.initials: LY
authors.lastname: Lin
authors.forename: Yau-Hua
authors.initials: YH
authors.lastname: Yu
authors.forename: Kuan-Han
authors.initials: KH
authors.lastname: Wu
authors.forename: Hsu-Ko
authors.initials: HK
authors.lastname: Kuo
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003430:Cross-Sectional Studies; D003920:Diabetes Mellitus / Q000453:epidemiology / Q000503:physiopathology; D005260:Female; D005684:Gait / Q000502:physiology*; D006306:Health Surveys; D006801:Humans; D007333:Insulin Resistance / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D009749:Nutrition Surveys; D014481:United States / Q000453:epidemiology; D016138:Walking / Q000502:physiology*