title: Relations between obesity, insulin resistance, and 25-hydroxyvitamin D.
abstract: BACKGROUND
  Although low circulating 25-hydroxyvitamin D [25(OH)D] concentrations have been associated with insulin resistance and obesity, the relations between these 3 variables have not been completely resolved.
  
  
  OBJECTIVE
  The objective was to compare circulating 25(OH)D concentrations in apparently healthy individuals who were matched for degree of obesity or insulin sensitivity.
  
  
  METHODS
  This was a case-control study in which 78 apparently healthy individuals were classified as being normal weight (NW) or obese (OB) on the basis of their BMI and as being insulin sensitive (IS) or insulin resistant (IR) on the basis of their steady state plasma glucose (SSPG) concentration during the insulin suppression test.
  
  
  RESULTS
  Groups did not differ in terms of age, sex distribution, race, or mean (± SD) plasma 25(OH)D concentration. Values for 25(OH)D were 32 ± 10, 30 ± 10, and 28 ± 8 ng/mL in NW-IS, OB-IS, and OB-IR groups, respectively. These concentrations were essentially identical when comparing IR with IS subjects matched for BMI or when comparing OB with NW subjects matched for SSPG. Concentrations of 25(OH)D ≤ 30 ng/mL were somewhat more common in OB subjects than in NW subjects (54% compared with 35%), but SSPG concentrations were not different within either the IR or IS groups when subgroups with 25(OH)D concentrations ≤ 30 or > 30 ng/mL were compared.
  
  
  CONCLUSIONS
  In 78 individuals, 47% of whom were vitamin D deficient or insufficient (≤ 30 ng/mL), 25(OH)D concentrations did not vary with differences in insulin sensitivity (SSPG concentration) when matched for BMI (OB-IR compared with OB-IS). Similarly, when matched for SSPG concentrations, plasma 25(OH)D concentrations were not different in NW or OB individuals (NW-IS compared with OB-IS).
authors.affiliation: Department of Medicine, Stanford University School of Medicine, Stanford, CA, USA.
authors.forename: Cynthia A
authors.initials: CA
authors.lastname: Lamendola
authors.forename: Danit
authors.initials: D
authors.lastname: Ariel
authors.forename: David
authors.initials: D
authors.lastname: Feldman
authors.forename: Gerald M
authors.initials: GM
authors.lastname: Reaven
mesh_terms: D000328:Adult; D001786:Blood Glucose / Q000032:analysis; D015992:Body Mass Index; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007333:Insulin Resistance; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000097:blood* / Q000503:physiopathology; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood / Q000503:physiopathology
chemical_list: D001786:Blood Glucose; D014807:Vitamin D; C104450:25-hydroxyvitamin D