Effect of vitamin D on HbA1c levels of children and adolescents with diabetes mellitus type 1

Minerva Pediatr. 2017 Oct;69(5):391-395. doi: 10.23736/S0026-4946.16.04145-1. Epub 2014 Nov 20.


Background: Studies show the relationship between vitamin D deficiency and glucose metabolism disorders. The aim of this study was the evaluation of the effect of vitamin D administration in management of diabetes mellitus type 1 (T1D).

Methods: We evaluated the effect of supplementation with vitamin D on HbA1c levels of children and adolescents with T1D. In this before-after study, 70 subjects with T1D were enrolled. Fasting serum 25-hydroxyvitamin D, calcium, phosphate, alkaline phosphatase, glucose and HbA1c were measured at the initiation and after the administration of 50,000 IU of vitamin D3 biweekly for 3 months. The results were then compared using paired t-test. Between 70 patients, five patients were excluded from the study because they did not completed the study and finally 65 subjects finished the study.

Results: Sixty-five patients including 35 children and 30 adolescents were recruited. Forty-three (66.1%) subjects had vitamin D deficiency (<30 ng/mL). Vitamin D administration leads to decrease of fast blood sugar and HbA1c levels significantly in treated group without effect on calcium and alkaline phosphatase levels. So, no significant alterations occurred in calcium and alkaline phosphatase levels after supplementation with vitamin D.

Conclusions: This study showed that HbA1c may be reduced by administration of vitamin D to children and adolescents with T1D without changing the dose of insulin.

MeSH terms

  • Adolescent
  • Alkaline Phosphatase / blood
  • Calcium / blood
  • Child
  • Child, Preschool
  • Cholecalciferol / administration & dosage*
  • Controlled Before-After Studies
  • Diabetes Mellitus, Type 1 / drug therapy*
  • Diabetes Mellitus, Type 1 / physiopathology
  • Dietary Supplements
  • Female
  • Glycated Hemoglobin / metabolism*
  • Humans
  • Infant
  • Insulin / administration & dosage
  • Male
  • Vitamin D / analogs & derivatives
  • Vitamin D / blood
  • Vitamin D Deficiency / complications
  • Vitamin D Deficiency / drug therapy*


  • Glycated Hemoglobin A
  • Insulin
  • Vitamin D
  • Cholecalciferol
  • 25-hydroxyvitamin D
  • Alkaline Phosphatase
  • Calcium