title: Diabetes, peripheral neuropathy, and lower-extremity function.
abstract: OBJECTIVE
  Diabetes among older adults causes many complications, including decreased lower-extremity function and physical disability. Diabetes can cause peripheral nerve dysfunction, which might be one pathway through which diabetes leads to decreased physical function. The study aims were to determine the following: (1) whether diabetes and impaired fasting glucose are associated with objective measures of physical function in older adults, (2) which peripheral nerve function (PNF) tests are associated with diabetes, and (3) whether PNF mediates the diabetes-physical function relationship.
  
  
  METHODS
  This study included 983 participants, age 65 years and older from the InCHIANTI study. Diabetes was diagnosed by clinical guidelines. Physical performance was assessed using the Short Physical Performance Battery (SPPB), scored from 0 to 12 (higher values, better physical function) and usual walking speed (m/s). PNF was assessed via standard surface electroneurographic study of right peroneal nerve conduction velocity, vibration and touch sensitivity. Clinical cutpoints of PNF tests were used to create a neuropathy score from 0 to 5 (higher values, greater neuropathy). Multiple linear regression models were used to test associations.
  
  
  CONCLUSIONS
  One hundred twenty-six (12.8%) participants had diabetes. Adjusting for age, sex, education, and other confounders, diabetic participants had decreased SPPB (β=-0.99; p<0.01), decreased walking speed (β=-0.1m/s; p<0.01), decreased nerve conduction velocity (β=-1.7m/s; p<0.01), and increased neuropathy (β=0.25; p<0.01) compared to non-diabetic participants. Adjusting for nerve conduction velocity and neuropathy score decreased the effect of diabetes on SPPB by 20%, suggesting partial mediation through decreased PNF.
authors.affiliation: Doctoral Program in Gerontology, University of Maryland Baltimore and Baltimore County, 660 West Redwood Street, Suite 200, Baltimore, MD 21201-1596, USA; Department of Epidemiology and Public Health, University of Maryland Baltimore, 660 W. Redwood St, Suite 200, Baltimore, MD 21201-1596, USA. Electronic address: nchiles@epi.umaryland.edu.
authors.forename: Nancy S
authors.initials: NS
authors.lastname: Chiles
authors.affiliation: Laboratory of Epidemiology and Population Sciences, National Institute on Aging, National Institutes of Health, 7201 Wisconsin Avenue, Gateway Building Suite 3C309, Bethesda, MD 20892-9205, USA.
authors.forename: Caroline L
authors.initials: CL
authors.lastname: Phillips
authors.affiliation: Department of Medical Sciences, University of Ferrara, Ferrara, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Volpato
authors.affiliation: Geriatric Rehabilitation Unit, Azienda Sanitaria di Firenze, Florence, Italy.
authors.forename: Stefania
authors.initials: S
authors.lastname: Bandinelli
authors.affiliation: Longitudinal Studies Section, Clinical Research Branch, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA.
authors.forename: Luigi
authors.initials: L
authors.lastname: Ferrucci
authors.affiliation: Department of Epidemiology and Public Health, University of Maryland Baltimore, 660 W. Redwood St, Suite 200, Baltimore, MD 21201-1596, USA.
authors.forename: Jack M
authors.initials: JM
authors.lastname: Guralnik
authors.affiliation: Department of Anesthesiology and Pain Medicine, University of Washington, Box 356540, 1959 NE Pacific Street, BB-1469, Seattle, WA 98195-6540, USA.
authors.forename: Kushang V
authors.initials: KV
authors.lastname: Patel
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D003920:Diabetes Mellitus / Q000453:epidemiology / Q000503:physiopathology*; D003929:Diabetic Neuropathies / Q000453:epidemiology / Q000503:physiopathology*; D005260:Female; D005684:Gait; D018149:Glucose Intolerance / Q000453:epidemiology / Q000503:physiopathology; D006801:Humans; D007558:Italy / Q000453:epidemiology; D035002:Lower Extremity / Q000503:physiopathology*; D008297:Male; D011236:Prediabetic State / Q000453:epidemiology / Q000503:physiopathology; D011597:Psychomotor Performance
keywords: Geriatrics; Gerontology; Lower extremity function; Peripheral neuropathy