Background & aim: The co-existence of vitamin D deficiency with obesity and type 2 diabetes is highly prevalent in the United Arab Emirates. We do not have studies evaluating the vitamin D dose response and sufficiency, and if sufficient substitution dose during a longer period could decrease obesity or change fat distribution in obese type 2 diabetic vitamin D deficient Emiratis.
Methods: A randomized double-blind clinical trial was conducted for 6 months followed by another 6 months of un-blinded follow up with 87 obese, type 2 diabetic participants. Serum 25-hydroxy vitamin D (S-25(OH)D), anthropometric data, and life-style factors such as diet and sunlight exposure were measured. The study was executed in 3 phases in two arms vitamin D arm (n = 45) and placebo arm (n = 42); in Phase 1 the vitamin D arm received 6000 IU vitamin D3/day (3 months) followed by Phase 2 with 3000 IU vitamin D3/day. During follow up (phase 3) both the arms were un-blinded and supplemented with 2200 IU vitamin D3/day for another 6 months.
Results: At the baseline a significant (p < 0.01) positive association between body fat mass and body weight (r = 0.97) muscle mass (r = 0.47), water mass (r = 0.54), waist circumference (r = 0.82) and serum PTH (r = 0.28) was observed. On supplementation no significant changes in anthropometric dimensions was observed. S-25(OH) D peaked in phase 1 (77.2 ± 30.1 vs 28.5 ± 9.2, p = 0.003) followed by a decrease in phase 2 (62.3 ± 20.8, p = 0.006) paralleled by a decrease in parathyroid hormone in phase 2 (5.9 ± 2.4 vs 4.5 ± 1.8, p < 0.01) compared to baseline in vitamin D group.
Conclusion: This study shows no significant influence of vitamin D supplementation on weight, fat mass or waist circumference in type 2 diabetic obese vitamin D deficient participants of Arab ethnicity after one year. Despite a relatively high daily dose of vitamin D3 we did not achieve target levels of S-25(OH)D above 75 nmol/L in this population. However, supplementation was safe, improved s- 25 (OH)D also reducing the incidence of eucalcemic parathyroid hormone elevation.
Clinical trial registry: ClinicalTrials.gov Identifier: NCT02101151.
Keywords: Body composition; Obesity; Type 2 diabetes; United Arab Emirates; Vitamin D.
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