High vs Low Dose Vitamin D in Patients With Diabetic Peripheral Neuropathy

Aim. To assess the effect of different doses of vitamin D supplementation on peripheral neuropathy in patients with type 2 diabetes mellitus (T2DM). 68 patients with T2DM and peripheral neuropathy will be randomized into two treatment groups: cholecalciferol 5,000 IU once/week and cholecalciferol 40,000 IU once/week orally for 24 weeks. Severity of neuropathy (neuropathy symptom score (NSS), neuropathy disability score (NDS), visual analog scale (VAS)), body mass index (BMI), glycated hemoglobin (HbA1c), 25-hydroxycalciferol (25(OH)D), parathyroid hormone (PTH), serum interleukins (IL) 1β, 6 and 10, C-reactive protein, tumor necrosis factor α and microcirculation (MC) parameters assessed before and after treatment. The initial and final indicators of the skin blood flow (M, σ, Kv) and MC parameters after postural and occlusal tests by laser Doppler flowmetry (LDF). Sixteen subjects without diabetes will represent the control group.