title: Low serum 25-hydroxyvitamin D level predicts progression to type 2 diabetes in individuals with prediabetes but not with normal glucose tolerance.
abstract: OBJECTIVE
  Vitamin D deficiency may increase the risk of type 2 diabetes. We therefore investigated whether serum concentrations of 25-hydroxyvitamin D [25(OH)D] would predict the development of prediabetes (impaired fasting glucose, impaired glucose tolerance or the two combined) and type 2 diabetes, either on their own or when combined with serum concentrations of IGF-1 or IGF-binding protein-1 (IGFBP-1), which may interact with 25(OH)D.
  
  
  METHODS
  At baseline, participants aged 35-56 years without known type 2 diabetes were examined using OGTTs, 25(OH)D and IGF peptide measurements, and anthropometric and lifestyle data. Participants who had prediabetes or type 2 diabetes at follow-up 8-10 years later were selected as cases; these were then age- and sex-matched to controls with normal glucose tolerance (NGT) at both baseline and follow-up, giving a total of 980 women and 1,398 men.
  
  
  RESULTS
  Men but not women in the highest quartile of 25(OH)D level had a decreased OR for developing type 2 diabetes after adjustment for confounders (OR 0.52, 95% CI 0.30, 0.90), an effect accounted for by individuals with prediabetes, but not with NGT, at baseline. In both sexes, progression from prediabetes to type 2 diabetes was reduced by about 25% per 10 nmol/l increase in 25(OH)D. A high IGFBP-1 value was a better predictor of a reduced risk of type 2 diabetes than high 25(OH)D for both sexes, whereas high IGF-1 concentrations predicted a decreased risk only in men.
  
  
  CONCLUSIONS
  High serum 25(OH)D concentrations predict a reduced risk of type 2 diabetes in individuals with prediabetes, but not NGT. There were no significant interactions between 25(OH)D and IGFBP-1 or IGF-1 in terms of risk of diabetes. Our data suggest that vitamin D supplementation should be evaluated for the prevention of type 2 diabetes in prediabetic individuals.
authors.affiliation: Department of Molecular Medicine and Surgery, Karolinska Institutet, Karolinska University Hospital, M1:03, SE-17176 Stockholm, Sweden. anna_deleskog@ki.se
authors.forename: A
authors.initials: A
authors.lastname: Deleskog
authors.forename: A
authors.initials: A
authors.lastname: Hilding
authors.forename: K
authors.initials: K
authors.lastname: Brismar
authors.forename: A
authors.initials: A
authors.lastname: Hamsten
authors.forename: S
authors.initials: S
authors.lastname: Efendic
authors.forename: C-G
authors.initials: CG
authors.lastname: Östenson
mesh_terms: D000328:Adult; D003924:Diabetes Mellitus, Type 2 / Q000097:blood* / Q000378:metabolism / Q000473:pathology; D005260:Female; D018149:Glucose Intolerance / Q000097:blood / Q000378:metabolism / Q000503:physiopathology; D005951:Glucose Tolerance Test; D006801:Humans; D008297:Male; D008875:Middle Aged; D011236:Prediabetic State / Q000097:blood* / Q000378:metabolism / Q000503:physiopathology*; D013002:Somatomedins / Q000378:metabolism; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood
chemical_list: D013002:Somatomedins; D014807:Vitamin D; C104450:25-hydroxyvitamin D