title: Effects of vitamin D repletion on glycemic control and inflammatory cytokines in adolescents with type 1 diabetes.
abstract: OBJECTIVE
  Little is known about the relationship between vitamin D deficiency and adolescents with type 1 diabetes. On the basis of adult studies showing that vitamin D improves insulin sensitivity and decreases inflammatory cytokines linked to microvascular complications, we hypothesized that treating vitamin D deficiency in adolescents with type 1 diabetes would improve glycemia and reduce inflammatory markers.
  
  
  METHODS
  This was a randomized, prospective, crossover study of 25 adolescents with type 1 diabetes for at least a year (aged: 13-21 yr; 62% female; 62% Hispanic) and vitamin D deficiency (25-OH vitamin D ≤30 ng/mL). Subjects received vitamin D3 (20 000 IU/week) for 6 months, either immediately or after 6 months of observation.
  
  
  RESULTS
  At baseline, 63% of subjects screened were vitamin D deficient and randomized. Interleukin-6 (IL-6) was significantly higher in the vitamin D deficient group compared with the sufficient group (medians: 0.36 vs. 0.18) (p = 0.026), whereas neither C-reactive protein (CRP) nor tumor necrosis factor-α (TNF-α) differed. Vitamin D treatment increased serum levels of 25-OH vitamin D from 22 ± 5.3 to 34.3 ± 12.1 ng/mL (p < 0.01). However, treatment did not affect glycated hemoglobin (HbA1c), insulin dosage, CRP, interleukin-6 (IL-6), or TNF-α.
  
  
  CONCLUSIONS
  Vitamin D deficiency is prevalent in the adolescent type 1 diabetes population, and could be associated with changes in inflammatory markers. However, vitamin D repletion over 6 months did not affect glycemia or markers of inflammation in our study, highlighting the need for additional research to validate these findings.
authors.affiliation: Center for Endocrinology, Diabetes and Metabolism, Children's Hospital Los Angeles, Los Angeles, CA, 90027, USA.
authors.forename: Erin M
authors.initials: EM
authors.lastname: Shih
authors.affiliation: Center for Endocrinology, Diabetes and Metabolism, Children's Hospital Los Angeles, Los Angeles, CA, 90027, USA.|Keck School of Medicine, University of Southern California, Los Angeles, CA, 90027, USA.
authors.forename: Steven
authors.initials: S
authors.lastname: Mittelman
authors.affiliation: Center for Endocrinology, Diabetes and Metabolism, Children's Hospital Los Angeles, Los Angeles, CA, 90027, USA.|Keck School of Medicine, University of Southern California, Los Angeles, CA, 90027, USA.
authors.forename: Pisit
authors.initials: P
authors.lastname: Pitukcheewanont
authors.affiliation: Keck School of Medicine, University of Southern California, Los Angeles, CA, 90027, USA.|Clinical and Translational Science Institute (CTSI), The Saban Research Institute, Children's Hospital Los Angeles, Los Angeles, CA, 90027, USA.
authors.forename: Colleen G
authors.initials: CG
authors.lastname: Azen
authors.affiliation: Center for Endocrinology, Diabetes and Metabolism, Children's Hospital Los Angeles, Los Angeles, CA, 90027, USA.|Keck School of Medicine, University of Southern California, Los Angeles, CA, 90027, USA.
authors.forename: Roshanak
authors.initials: R
authors.lastname: Monzavi
mesh_terms: D000293:Adolescent; D015415:Biomarkers / Q000097:blood; D001786:Blood Glucose / Q000378:metabolism*; D002762:Cholecalciferol / Q000008:administration & dosage*; D018592:Cross-Over Studies; D016207:Cytokines / Q000097:blood*; D003922:Diabetes Mellitus, Type 1 / Q000097:blood / Q000150:complications*; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D007249:Inflammation / Q000097:blood*; D008297:Male; D011446:Prospective Studies; D014807:Vitamin D; D014808:Vitamin D Deficiency / Q000097:blood / Q000150:complications / Q000188:drug therapy*; D014815:Vitamins / Q000008:administration & dosage; D055815:Young Adult
chemical_list: D015415:Biomarkers; D001786:Blood Glucose; D016207:Cytokines; D014815:Vitamins; D014807:Vitamin D; D002762:Cholecalciferol
keywords: adolescents; inflammatory cytokines; microvascular complications; type 1 diabetes; vitamin D