Vitamin D3 supplementation, bone health and quality of life in adults with diabetes and chronic kidney disease: Results of an open label randomized clinical trial

Background: Adults with diabetes (DM) and chronic kidney disease (CKD) are at risk for vitamin D (vitD) insufficiency, suboptimal bone health and reduced quality of life (QoL) due to limited sunlight exposure, poor vitD intake and CKD. Aims: This open-labeled, randomized clinical trial, compared the impact of daily (2000 IU/D) verses monthly (40,000 IU/month) vitD3 supplementation over six months on markers of vitD status, bone health and QoL in adults with DM and CKD (stages: 1-4). Methods: Participants (18-80 years) were randomized to daily (n = 60) or monthly (n = 60) vitD3 for six months. Primary outcomes included: vitD status (25-hydroxyvitD [25(OH)D], 1, 25-dihydroxyvitD [1,25(OH)214 bone health (bone mineral density [BMD] and serum concentrations of bone -specific alkaline phosphatase [BSAP], osteocalcin [OC], N-telopeptide-type 1 -collagen [NTx]) and Fibroblast Growth Factor -23 (FGF-23). Secondary outcomes included QoL (Short Form -36 questionnaire). Results: Adherence by dose allocation over six months was 95.0 -1- 5.7% (daily) and 94.1 4.1% (monthly), respectively (p = 0.44); resulting in an overall median [95% CI] increase in serum 25(OH)D of 19 (12 26) nmol/L (p < 0.001). Serum 25(OH)D increased at three (p < 0.001) and six months (p < 0.001) in the daily and monthly groups, respectively. No significant differences over six months between groups were observed in serum concentrations of 1,25(OH)2D, FGF-23, OC and NTx, BMD and QoL measures (p > 0.05). Serum 25(OH)D > 75 nmol/L was associated with significant reductions in BSAP (p = 0.01) and improved physical functioning vs those with concentrations < 75 nmol/L (62.5 +/- 26.8 vs 52.7 +/- 26.3; p = 0.03) in the monthly and daily groups, respectively. Conclusions: Daily (2000 IU/D) and monthly (40,000 IU/month) vitD3 supplementation for six months in adults with DM and CKD was safe, and resulted in equivalent adherence and improvements in overall vitD status, but only modest changes in markers of bone health and QoL. (C) 2016 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.