title: Quadriceps strength, quadriceps power, and gait speed in older U.S. adults with diabetes mellitus: results from the National Health and Nutrition Examination Survey, 1999-2002.
abstract: OBJECTIVE
  To examine the independent association between diabetes mellitus (and its duration and severity) and quadriceps strength, quadriceps power, and gait speed in a national population of older adults.
  
  
  METHODS
  Cross-sectional nationally representative survey.
  
  
  METHODS
  United States.
  
  
  METHODS
  Two thousand five hundred seventy-three adults aged 50 and older in the National Health and Nutrition Examination Survey 1999-2002 who had assessment of quadriceps strength.
  
  
  METHODS
  Diabetes mellitus was ascertained according to questionnaire. Measurement of isokinetic knee extensor (quadriceps) strength was performed at 60º/s. Gait speed was assessed using a 20-foot walk test. Multiple linear regression analyses were used to assess the association between diabetes mellitus status and outcomes, adjusting for potential confounders or mediators.
  
  
  RESULTS
  Older U.S. adults with diabetes mellitus had significantly slower gait speed (0.96 ± 0.02 m/s) than those without (1.08 ± 0.01 m/s; P < .001). After adjusting for demographic characteristics, weight, and height, diabetes mellitus was also associated with significantly lower quadriceps strength (-4.6 ± 1.9 Nm; P = .02) and power (-4.9 ± 2.0 W; P = .02) and slower gait speed (-0.05 ± 0.02 m/s; P = .002). Associations remained significant after adjusting for physical activity and C-reactive protein. After accounting for comorbidities (cardiovascular disease, peripheral neuropathy, amputation, cancer, arthritis, fracture, chronic obstructive pulmonary disease), diabetes mellitus was independently associated only with gait speed (-0.04 ± 0.02 m/s; P = .02). Diabetes mellitus duration in men and women was negatively associated with age-adjusted quadriceps strength (-5.7 and -3.5 Nm/decade of diabetes mellitus, respectively) and power (-6.1 and -3.8 W/decade of diabetes mellitus, respectively) (all P ≤ .001, no significant interactions according to sex). Glycosylated hemoglobin was not associated with outcomes after accounting for body weight.
  
  
  CONCLUSIONS
  Older U.S. adults with diabetes mellitus have lower quadriceps strength and quadriceps power that is related to the presence of comorbidities and walk slower than those without diabetes mellitus. Future studies should investigate the relationship between hyperglycemia and subsequent declines in leg muscle function.
authors.affiliation: Division of Endocrinology and Metabolism, The Johns Hopkins University, Baltimore, Maryland 21287, USA. rrastogi@jhmi.edu
authors.forename: Rita Rastogi
authors.initials: RR
authors.lastname: Kalyani
authors.forename: Yolande
authors.initials: Y
authors.lastname: Tra
authors.forename: Hsin-Chieh
authors.initials: HC
authors.lastname: Yeh
authors.forename: Josephine M
authors.initials: JM
authors.lastname: Egan
authors.forename: Luigi
authors.initials: L
authors.lastname: Ferrucci
authors.forename: Frederick L
authors.initials: FL
authors.lastname: Brancati
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*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009017:Morbidity; D053580:Muscle Strength / Q000502:physiology*; D009749:Nutrition Surveys / Q000379:methods*; D052097:Quadriceps Muscle / Q000503:physiopathology*; D012189:Retrospective Studies; D011795:Surveys and Questionnaires; D014481:United States / Q000453:epidemiology; D016138:Walking / Q000502:physiology*