Takeaway
- This study found a significant reduction in 25-hydroxyvitamin D [25(OH)D] levels in patients with painful diabetic peripheral neuropathy (DPN), suggesting a possible role for vitamin D in the pathogenesis of painful DPN.
- Further prospective and intervention trials are required to prove causality between low vitamin D levels and painful DPN.
Why this matters
- Recent studies have demonstrated an association between low vitamin D levels and DPN; however, most of them have not differentiated between painful and painless DPN or assessed major confounding factors including seasonal sunlight exposure, daily activity, and intra-epidermal nerve density.
Study design
- Patients with type 2 diabetes mellitus were categorised into 3 groups: 17 with painful DPN, 14 with painless DPN and 14 without DPN.
- Healthy volunteers along with patients with T2DM underwent clinical and neurological assessments.
- Vitamin D levels, sunlight exposure, and daily activity were measured in all participants.
- Funding: Sheffield Teaching Hospitals NHS Foundation Trust.
Key results
- After adjustment for confounders, significantly lower 25(OH)D levels were observed in painful DPN (34.9 nmol/L), painless DPN (53.1 nmol/L), no DPN (49.6 nmol/L) and healthy volunteers (62.05 nmol/L).
- Each unit reduction in vitamin D level was associated with increased odds of painful DPN by a factor of 1.11 (95% CI, 1.0-1.11).
- There were significant correlations between low 25(OH)D levels and lower cold detection thresholds (r=0.39; P=.02) and subepidermal nerve fibre densities (r=0.42; P=.01).
Limitations
- Relatively small cohort size.
- Cross-sectional design.
References
References