title: Serum Vitamin D Concentrations Are Not Associated with Insulin Resistance in Swiss Adults.
abstract: BACKGROUND
  Low vitamin D status has been associated with an increased risk of developing type 2 diabetes and insulin resistance (IR), although this has been recently questioned.
  
  
  OBJECTIVE
  We examined the association between serum vitamin D metabolites and incident IR.
  
  
  METHODS
  This was a prospective, population-based study derived from the CoLaus (Cohorte Lausannoise) study including 3856 participants (aged 51.2 ± 10.4 y; 2217 women) free from diabetes or IR at baseline. IR was defined as a homeostasis model assessment (HOMA) index >2.6. Fasting plasma insulin and glucose were measured at baseline and at follow-up to calculate the HOMA index. The association of vitamin D metabolites with incident IR was analyzed by logistic regression, and the results were expressed for each independent variable as ORs and 95% CIs.
  
  
  RESULTS
  During the 5.5-y follow-up, 649 (16.9%) incident cases of IR were identified. Participants who developed IR had lower baseline serum concentrations of 25-hydroxyvitamin D3 [25(OH)D3 (25-hydroxycholecalciferol); 45.9 ± 22.8 vs. 49.9 ± 22.6 nmol/L; P < 0.001], total 25(OH)D3 (25(OH)D3 + epi-25-hydroxyvitamin D3 [3-epi-25(OH)D3]; 49.1 ± 24.3 vs. 53.3 ± 24.1 nmol/L; P < 0.001), and 3-epi-25(OH)D3 (4.2 ± 2.9 vs. 4.3 ± 2.5 nmol/L; P = 0.01) but a higher 3-epi- to total 25(OH)D3 ratio (0.09 ± 0.05 vs. 0.08 ± 0.04; P = 0.007). Multivariable analysis adjusting for month of sampling, age, and sex showed an inverse association between 25(OH)D3 and the likelihood of developing IR [ORs (95% CIs): 0.86 (0.68, 1.09), 0.60 (0.46, 0.78), and 0.57 (0.43, 0.75) for the second, third, and fourth quartiles compared with the first 25(OH)D3 quartile; P-trend < 0.001]. Similar associations were found between total 25(OH)D3 and incident IR. There was no significant association between 3-epi-25(OH)D3 and IR, yet a positive association was observed between the 3-epi- to total 25(OH)D3 ratio and incident IR. Further adjustment for body mass index, sedentary status, and smoking attenuated the association between 25(OH)D3, total 25(OH)D3, and the 3-epi- to total 25(OH)D3 ratio and the likelihood of developing IR.
  
  
  CONCLUSIONS
  In the CoLaus study in healthy adults, the risk of incident IR is not associated with serum concentrations of 25(OH)D3 and total 25(OH)D3.
authors.affiliation: Department of Internal Medicine.
authors.forename: Pedro
authors.initials: P
authors.lastname: Marques-Vidal
authors.affiliation: Department of Internal Medicine.
authors.forename: Peter
authors.initials: P
authors.lastname: Vollenweider
authors.affiliation: Institute of Social and Preventive Medicine (IUMSP), Unit of Population Epidemiology, Division of Primary Care Medicine, Department of Community Medicine, Primary Care and Emergency Medicine, Geneva University Hospitals, Geneva, Switzerland; and Department of Epidemiology, Rollins School of Public Health, Emory University, Atlanta, GA.
authors.forename: Idris
authors.initials: I
authors.lastname: Guessous
authors.affiliation: Department of Laboratory Medicine, and.
authors.forename: Hugues
authors.initials: H
authors.lastname: Henry
authors.affiliation: Department of Laboratory Medicine, and.
authors.forename: Olivier
authors.initials: O
authors.lastname: Boulat
authors.affiliation: Department of Internal Medicine.
authors.forename: Gérard
authors.initials: G
authors.lastname: Waeber
authors.affiliation: Service of Endocrinology, Diabetes, and Metabolism, Lausanne University Hospital, Lausanne, Switzerland; francois.jornayvaz@chuv.ch.
authors.forename: François R
authors.initials: FR
authors.lastname: Jornayvaz
mesh_terms: D000328:Adult; D001786:Blood Glucose / Q000378:metabolism; D015992:Body Mass Index; D002112:Calcifediol / Q000097:blood*; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000453:epidemiology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D015995:Prevalence; D011446:Prospective Studies; D013557:Switzerland / Q000453:epidemiology; D014808:Vitamin D Deficiency / Q000097:blood* / Q000453:epidemiology*
chemical_list: D001786:Blood Glucose; D007328:Insulin; D002112:Calcifediol
keywords: HOMA; body mass index; insulin resistance; prospective study; type 2 diabetes; vitamin D