Vitamin D supplementation in obese type 2 diabetes subjects in Ajman, UAE: a randomized controlled double-blinded clinical trial

Randomized, double-blind, placebo-controlled trial in obese adults with type 2 diabetes and vitamin D deficiency (25(OH)D ≤ 50 nmol/L), aged 30–60 years, BMI ≥30 kg/m2; UAE nationals; 87 participants randomized (Vitamin D group n=45; placebo group n=42).

Vitamin D3 (cholecalciferol): 6000 IU/day for 3 months, followed by 3000 IU/day for 3 months; orally in capsules.

Vitamin D3 supplementation raised serum 25(OH)D to 77.2 ± 30.1 nmol/L after 3 months and 62.3 ± 20.8 nmol/L after 6 months (vs baseline, P<0.01). Parathyroid hormone decreased to 4.5 ± 1.8 pmol/L by month 6 (vs baseline 5.9 ± 2.4, P=0.003). No significant changes in fasting glucose, HbA1c, C‑peptide, lipids, CRP, creatinine, calcium, phosphorus, alkaline phosphatase, or TSH in either group. Six months of vitamin D3 normalized vitamin D status and reduced PTH but showed no effect on metabolic control.

Small, single-population study (obese Emirati adults with type 2 diabetes); 6-month duration; adherence ~85%; not all participants achieved sustained 25(OH)D >75 nmol/L; potential interactions with concomitant medications; limited generalizability.