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25(OH) Vitamin D Levels and Severity of Type 1 Diabetes in Youth and Adults With Recent-Onset Disease

Baidal DA, Alvarez AM, Padilla N, Sanchez J, Lanzoni G, Alejandro R, Ricordi C

Journal of the Endocrine Society, 2025

18 participants

Abstract

OBJECTIVE: To test 25-hydroxy vitamin D (25(OH)D) levels among subjects with new-onset type 1 diabetes (T1D) and their association with fasting and stimulated C-peptide at study entry in an open-label randomized trial.

METHODS: We conducted a post hoc secondary analysis of the POSEIDON trial (a Pilot, Safety and Feasibility Trial of High-Dose Omega-3 fatty acids and High-Dose Cholecalciferol Supplementation in Type 1 Diabetes). Eligibility criteria included age 6 to 65 years, T1D of up to 10 years duration, presence of at least 1 islet autoantibody, and stimulated C-peptide ≥0.066 pmol/mL. A total of 18 subjects with new-onset T1D (defined as ≤180 days duration) with paired 25(OH)D levels and a 4-hour mixed meal tolerance test (MMTT) at screening were included.

RESULTS: 25(OH)D levels were directly associated with fasting C-peptide (r = 0.589; 95% CI 0.154-0.833; P = .01) but no significant associations were found with MMTT stimulated C-peptide. Ten subjects had 25(OH)D levels 30 ng/mL (0.22 ± 0.14 vs 0.41 ± 0.09 pmol/mL; P < .006).

CONCLUSION: 25(OH)D levels were directly associated with fasting C-peptide in youth and adults with newly diagnosed T1D. Low 25(OH)D levels may be associated with more aggressive autoimmunity in patients at risk for T1D potentially leading to a lower beta-cell mass at T1D clinical onset, but larger studies are required to validate these results.

How strong is the evidence?

Evidence Hub reads this as a randomized trial, done in people. Its evidence level is 3 of 5 (Moderate · trial / cohort / secondary analysis). Trials without a large randomized design, cohorts and secondary analyses give moderate evidence. Reported size: 18 participants or records.

How the five levels of evidence work. The level is assigned automatically from the abstract and can be wrong, so check the paper.

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