Independent Effects of Vitamin D on Leukocyte Telomere Length and Activity: An RCT in Asian Indian Women With Prediabetes

INTRODUCTION: Prediabetes is increasing in India and progresses rapidly to type 2 diabetes. The impact of vitamin D3 supplementation on telomerase activity and leukocyte telomere length (LTL) among people with prediabetes has been poorly researched. RESEARCH DESIGN AND METHODS: In this 18-month prospective trial, we enrolled 121 women with prediabetes and randomized them into intervention (vitamin D3 supplementation, n = 61) and placebo (n = 60) groups. LTL and telomerase activity were measured. RESULTS: In the current study, LTL and telomerase activity were assessed at visit 1 (week 0), visit 2 (week 52), and visit 3 (week 78). LTL increased significantly in the intervention group by week 52 (P = .004) and became more pronounced at week 78 (P = .001), representing a 14.5% increase from baseline. Similarly, telomerase activity showed progressive enhancement with vitamin D treatment, achieving significance by week 52 (P = .001) and continuing through week 78 (P < .0001), reflecting a 16.2% increase from baseline. Within-group analysis confirmed significant improvements over time in the vitamin D group (P = .002) but not in placebo (P = .18) group. After adjusting for potential confounders including body mass index, subscapular skinfold thickness, fasting blood glucose, and PTH, serum 25-hydroxyvitamin D levels maintained a significant independent association with both LTL (OR = 2.053; 95% CI, 1.410-2.243; P = .001) and telomerase activity (OR = 2.032; 95% CI, 1.410-2.254; P = .001) in the intervention group. CONCLUSION: Vitamin D supplementation, over 78 weeks, is independently associated with increased LTL and telomerase activity in Asian Indian women with prediabetes.