title: Plasma 25-hydroxyvitamin D levels are favorably associated with β-cell function.
abstract: OBJECTIVE
  The association of hypovitaminosis D with type 2 diabetes is well recognized. Although hypovitaminosis D is associated with insulin resistance, there is much less information about its impact on β-cell function in humans.
  
  
  METHODS
  We enrolled 150 healthy, glucose-tolerant subjects for the assessment of β-cell function (acute insulin response) and insulin sensitivity index (ISI) using a hyperglycemic clamp. Adjusted β-cell function (ABCF) was defined as the product of acute insulin response and ISI. The relations of plasma 25-hydroxyvitamin D [25(OH)D] level with insulin sensitivity and ABCF were examined.
  
  
  RESULTS
  Plasma 25(OH)D levels were positively associated with ABCF (P = 0.00004) and ISI (P < 0.00001). The associations remained significant after adjustment for age, sex, body mass index, physical activity, ethnicity, and season of study.
  
  
  CONCLUSIONS
  Plasma 25(OH)D levels are positively association with both β-cell function and insulin sensitivity. Our observations suggest the roles of vitamin D deficiency in the dual defect of type 2 diabetes.
authors.affiliation: Department of Clinical Diabetes, Endocrinology, and Metabolism, City of Hope National Medical Center, Duarte, CA, USA.
authors.forename: Rudruidee
authors.initials: R
authors.lastname: Karnchanasorn
authors.forename: Horng-Yih
authors.initials: HY
authors.lastname: Ou
authors.forename: Ken C
authors.initials: KC
authors.lastname: Chiu
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D015415:Biomarkers / Q000097:blood; D016009:Chi-Square Distribution; D003430:Cross-Sectional Studies; D003924:Diabetes Mellitus, Type 2 / Q000097:blood* / Q000503:physiopathology; D005260:Female; D015309:Glucose Clamp Technique; D005951:Glucose Tolerance Test; D006801:Humans; D007328:Insulin / Q000097:blood*; D007333:Insulin Resistance; D050417:Insulin-Secreting Cells / Q000378:metabolism*; D016018:Least-Squares Analysis; D015141:Los Angeles; D008297:Male; D011237:Predictive Value of Tests; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood* / Q000503:physiopathology
chemical_list: D015415:Biomarkers; D007328:Insulin; D014807:Vitamin D; C104450:25-hydroxyvitamin D