title: Role of muscle mass and muscle quality in the association between diabetes and gait speed.
abstract: OBJECTIVE
  Older people with type 2 diabetes are at high risk of mobility disability. We investigated the association of diabetes with lower-limb muscle mass and muscle quality to verify whether diabetes-related muscle impairments mediate the association between diabetes and low walking speed.
  
  
  METHODS
  We performed a cross-sectional analysis of 835 participants (65 years old and older) enrolled in the InCHIANTI (Invecchiare in Chianti, aging in the Chianti area) population-based study. Total, muscular, and fat cross-sectional areas of the calf and relative muscle density were measured using peripheral quantitative computerized tomography. Indicators of muscle performance included knee-extension torque, ankle plantar flexion and dorsiflexion strength, lower-extremity muscle power, and ankle muscle quality (ratio of ankle strength to the muscle area [kilograms per centimeters squared]). Gait performance was assessed by 4- and 400-m walking speed. Diabetes was ascertained by standard American Diabetes Association criteria.
  
  
  RESULTS
  Prevalence of diabetes was 11.4%. After adjustment for age and sex, participants with diabetes had lower muscle density, knee and ankle strength, and muscle power and worse muscle quality (all P < 0.05). Diabetic participants were also slower on both 4-m (β: -0.115 ± 0.024 m/s, P < 0.001) and 400-m (β:-0.053 ± 0.023 m/s, P < 0.05) walking tests. In multivariable linear regression models, lower-limb muscle characteristics accounted for 24.3 and 15.1% of walking speed difference comparing diabetic and nondiabetic subjects in the 4- and 400-m walks, respectively.
  
  
  CONCLUSIONS
  In older persons, diabetes is associated with reduced muscle strength and worse muscle quality. These impairments are important contributors of walking limitations related to diabetes.
authors.affiliation: Section of Internal Medicine and Geriatrics, Department of Clinical and Experimental Medicine, University of Ferrara, Ferrara, Italy. vlt@unife.it
authors.forename: Stefano
authors.initials: S
authors.lastname: Volpato
authors.forename: Lara
authors.initials: L
authors.lastname: Bianchi
authors.forename: Fulvio
authors.initials: F
authors.lastname: Lauretani
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Lauretani
authors.forename: Stefania
authors.initials: S
authors.lastname: Bandinelli
authors.forename: Jack M
authors.initials: JM
authors.lastname: Guralnik
authors.forename: Giovanni
authors.initials: G
authors.lastname: Zuliani
authors.forename: Luigi
authors.initials: L
authors.lastname: Ferrucci
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003430:Cross-Sectional Studies; D003924:Diabetes Mellitus, Type 2 / Q000503:physiopathology; D005260:Female; D005684:Gait / Q000502:physiology*; D006801:Humans; D008297:Male; D053580:Muscle Strength / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology*