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

Introduction Prediabetes is increasing in India and progresses rapidly to type 2 diabetes (T2D). 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. Leukocyte telomere length (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=0.004) and became more pronounced at week 78 (p=0.001), representing a 14.5% increase from baseline. Similarly, telomerase activity showed progressive enhancement with vitamin D treatment, achieving significance by week 52 (p=0.001) and continuing through week 78 (p<0.0001), reflecting a 16.2% increase from baseline. Within-group analysis confirmed significant improvements over time in the vitamin D group (p=0.002) but not in placebo (p=0.18). After adjusting for potential confounders including BMI, subscapular skinfold thickness, fasting blood glucose, and parathyroid hormone, serum 25(OH)D levels maintained a significant independent association with both LTL (OR=2.053, 95% CI: 1.410-2.243, p=0.001) and telomerase activity (OR=2.032, 95% CI: 1.410-2.254, p=0.001) 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.