Endocrine Abstracts

Background

Vitamin D deficiency seems to be more prevalent among diabetic patients with distal symmetrical polyneuropathy. Besides, those patients have a lower pain threshold; there is a shortage of data concerning pre-diabetic individuals with peripheral neuropathy (PN).

Aim

First, to study the association of vitamin D deficiency with PN severity. Second, to determine the effect of vitamin D supplementation on PN in pre-diabetics.

Methods

178 pre-diabetic individuals aged18–60 years were recruited from outpatient department of the National Institute of Diabetes and Endocrinology, Cairo, Egypt; 89 patients with and 89 patients without PN (group A and group B, respectively).All patients werescreened for PN using 10 g monofilament, tuning fork, ankle reflex and pinprick test.In the first visit, baselineneuropathic total pain score and severity were assessed for group A, by Douleur Neuropathic 4 diagnostic questionnaire (DN4) and Short-form McGill Pain Questionnaire(SF-MPQ), respectively.In addition, serum 25- hydroxyvitamin D, ionized calcium, phosphorus, PTH, HbA1c, fasting blood glucose (FBG), 2hrs post 75 g glucose (2hr PPBG), creatinine, thyroid function test and lipid profile were measured for both groups. Prediabetic patients with PN were given vitamin D3 200.000IU IM monthly for 3 months. They were assessed clinically in 3 subsequent visits, one month apart. In the last visit all the laboratory measures, DN4 and (SF-MPQ) were repeated.

Results

None of the patients in both groups had sufficient vitamin D status.Vitamin D deficiency was highly prevalent among both groups, where 79.8% and 89.9% were deficient; 20.2% and 10.1% were insufficient among group A and group B respectively, P value 0.001.Nonetheless, there was insignificant difference in vitamin D levels between group A and group B (14 ± 6.4 and 14.6 ± 4, P = 0.4).Vitamin D level was negatively correlated with peripheral neuropathic total pain score and severity (r = –0.65, –0.47 respectively, P < 0.001) among group A. Moreover, vitamin D level was an independent predictor of neuropathic pain severity (odds ratio –0.18, 95% CI –0.33 –0.03, P = 0.018) after adjustment for age, BMI, FBG, 2hr PPBG, HbA1c, lipid profile, serum ionized calcium, phosphorus, PTH and TSH. Supplementation of vitamin D resulted in a highly significant improvement in FBG, 2hr PPBG, HbA1cand lipid profile, P < 0.001. Interestingly, total pain scoreand severity before vitamin D supplementation was (6.4 ± 1.6 and 28.3 ± 7.2, respectively ) and after was(2.5 ± 0.9 and 17 ± 6.3, respectively, P < 0.001).

Conclusion

Vitamin D deficiency is prevalent among prediabetics and can be considered an independent risk factor for painful PN in those patients. Correction of vitamin D deficiency improves glycemic parameters and severity of peripheral neuropathy.