VDR and diabetic neuropathy: Celikbilek et al. in their study examined the relationships between serum vitamin D, VDBP and VDR, and diabetic neuropathy, finding that patients with diabetic neuropathy had significantly lower levels of vitamin D than patients without neuropathy, while the values of VDBP and VDR were similar between the two groups (diabetic patients with and without neuropathy) [27].