No Protective Effect of Calcitriol on β-Cell Function in Recent-Onset Type 1 Diabetes


  1. the IMDIAB Group*
  1. 1Department of Endocrinology and Diabetes, Bambino Gesù Children's Hospital, Rome, Italy;
  2. 2Department of Diabetology, Catholic University, Rome, Italy;
  3. 3Department of Endocrinology and Diabetes, University Campus Bio-Medico, Rome, Italy;
  4. 4Department of Diabetology, Sandro Pertini Hospital, Rome, Italy;
  5. 5Department of Medical Therapy, University Sapienza, Rome, Italy.
  1. Corresponding author: Paolo Pozzilli, p.pozzilli{at}


OBJECTIVE We investigated whether supplementation of the active form of vitamin D (calcitriol) in recent-onset type 1 diabetes can protect β-cell function evaluated by C-peptide and improve glycemic control assessed by A1C and insulin requirement.

RESEARCH DESIGN AND METHODS Thirty-four subjects (aged 11–35 years, median 18 years) with recent-onset type 1 diabetes and high basal C-peptide >0.25 nmol/l were randomized in a double-blind trial to 0.25 μg/day calcitriol or placebo and followed-up for 2 years.

RESULTS At 6, 12, and 24 months follow-up, A1C and insulin requirement in the calcitriol group did not differ from the placebo group. C-peptide dropped significantly (P < 0.001) but similarly in both groups, with no significant differences at each time point.

CONCLUSIONS At the doses used, calcitriol is ineffective in protecting β-cell function in subjects (including children) with recent-onset type 1 diabetes and high C-peptide at diagnosis.


  • *A complete list of the members of the IMDIAB Group can be found in the appendix.

  • Clinical trial registry no. NCT01120119,

  • The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

  • Received May 10, 2010.
  • Accepted June 9, 2010.

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