Abstract

There is an association between serum vitamin D level and diabetic polyneuropathy. Topical vitamin D has been proposed for treatment of neuropathic pain in diabetics. The relationship between the serum 25-hydroxyvitamin D level and diabetic neuropathy has never been evaluated. The objective of the study was to evaluate a quantitative and qualitative relationship between the serum 25-hydroxyvitamin D level and diabetic polyneuropathy. This was a case -control study and the study was conducted on an outpatient basis. Twenty two (22) subjects were recruited from the Diabetes Clinic at Dartmouth Hitchcock Medical Center. All subjects had type-2 diabetes (male and female, 50-80 years old). The Michigan Neuropathy Screening Instrument (15 point questionnaire) was used to identify patients with neuropathy (score > 7/15). 11 patients did not have neuropathy and were designated the control group. 11 patients did have neuropathy (“study group”) and these patients underwent a detailed quantitative neuropathy evaluation by a neurologist using the 46-point Michigan Diabetic Neuropathy Scale (MDNS) and nerve conduction studies. We measured the serum 25-hydroxyvitamin D concentrations with liquid chromatography-tandem mass spectrometry (LC/MS) chromatography in all patients.  These values were compared between the control and study group, and were correlated with the detailed neuropathy score in the study group. Patients with diabetic polyneuropathy had a lower mean serum 25-hydroxyvitamin D level (21. 36 ng/ml with the SD of: 8.56) in comparison to the controls (36.18 ng/ml with the SD of 7.53). However, there was no correlation between the vitamin D level and the detailed quantitative neuropathy score in the study group. There is an association between serum 25-hydroxyvitamin D level and diabetic polyneuropathy. The quantitative association of serum vitamin D level with the severity of diabetic polyneuropathy requires further investigation and possible larger number of patients.

Key words: Serumvitamin D, diabetic polyneuropathy, neuropathy, 25-hydroxyvitamin D.