Effects of vitamin D repletion on glycemic control and inflammatory cytokines in adolescents with type 1 diabetes

Pediatr Diabetes. 2016 Feb;17(1):36-43. doi: 10.1111/pedi.12238. Epub 2014 Dec 18.


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.

Research design and 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.

Keywords: adolescents; inflammatory cytokines; microvascular complications; type 1 diabetes; vitamin D.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Adolescent
  • Biomarkers / blood
  • Blood Glucose / metabolism*
  • Cholecalciferol / administration & dosage*
  • Cross-Over Studies
  • Cytokines / blood*
  • Diabetes Mellitus, Type 1 / blood
  • Diabetes Mellitus, Type 1 / complications*
  • Dose-Response Relationship, Drug
  • Female
  • Humans
  • Inflammation / blood*
  • Male
  • Prospective Studies
  • Vitamin D
  • Vitamin D Deficiency / blood
  • Vitamin D Deficiency / complications
  • Vitamin D Deficiency / drug therapy*
  • Vitamins / administration & dosage
  • Young Adult


  • Biomarkers
  • Blood Glucose
  • Cytokines
  • Vitamins
  • Vitamin D
  • Cholecalciferol