Neuropathic pain is not associated with serum vitamin D but is associated with female gender in patients with type 2 diabetes mellitus

OBJECTIVE: Neuropathic pain is a common complication of diabetes mellitus (DM). Patients may complain of several neuropathic symptoms including impaired peripheral sensation, numbness, tingling, burning, and pain. Because these symptoms may cross with symptoms of vitamin D deficiency, we hypothesized that neuropathic pain and vitamin D deficiency may be associated in patients with type 2 DM. RESEARCH DESIGN AND METHODS: This is a cross-sectional study that involved 239 participants with type 2 DM. Neuropathic pain was assessed using PainDETECT questionnaire. Serum 25-hydroxyvitamin D was measured by the electrochemiluminescence immunoassay, fasting blood glucose was measured by the hexokinase method and hemoglobin A1c was measured by the turbidimetric inhibition immunoassay. RESULTS: The prevalence of neuropathic pain among type 2 DM participants was 26.8%. Vitamin D deficiency was reported in 67.8% of type 2 DM participants. The neuropathy score for females was significantly higher than that for males (p<0.01). There was no significant difference in serum vitamin D between type 2 DM participants according to their gender and according to their neuropathy status (p>0.05). Ordinal logistic regression analysis has shown that female gender was the only significant predictor of neuropathic pain among type 2 DM participants (p<0.01 with an OR (95% CI) of 2.45 (1.29 to 4.67)). CONCLUSIONS: Neuropathic pain was not associated with serum vitamin D but was associated with female gender in type 2 DM. Because our results were not consistent with other studies that used different neuropathy assessment tools, we suggest that further research should be conducted to check the validity of these tools in identifying subjects with neuropathy.