Clinical Observation of Adding Vitamin D to a Probucol-Based Regimen in Diabetic Nephropathy Patients

This study aimed to investigate the therapeutic efficacy of vitamin D as an adjunct to probucol-based triple therapy (valsartan + atorvastatin + probucol) in patients with diabetic nephropathy (DN) and to evaluate its impact on immune function. A total of 150 DN patients (Mogensen stage III) were retrospectively enrolled from July 2022 to May 2024. Based on the different medication regimens received in clinical practice, they were divided into a control group (n = 56) receiving triple therapy (valsartan + atorvastatin + probucol) and an observation group (n = 94) receiving quadruple therapy (triple therapy + vitamin D). Group assignment was determined by the actual treatment administered, not by randomization. Both groups received daily insulin infusions concurrently for 8 months. Clinical parameters, including renal function (SCr, 24 h UPE, UAlb/UCR), glucose and lipid profiles, immune markers (CD3+, CD4+ cells, CD4+/CD8+ ratio), and inflammatory factors (hs-CRP, IL-6, TNF-α, MCP-1), were assessed pre- and post-treatment. Results demonstrated that the observation group showed significantly greater improvements in renal function, glycemic control, lipid profiles, and immune modulation (elevated proportions of CD3+ and CD4+, a higher CD4+/CD8+ ratio, and reduced inflammatory markers) compared with the control group (all P <0.05). Regarding clinical discharge, the observation group showed a higher rate (45.74% vs. 39.29%), but this difference was not statistically significant (χ² = 0.596, P = 0.440). In conclusion, the addition of vitamin D was associated with greater clinical benefits than probucol-based triple therapy alone in this retrospective cohort of DN patients, including improvements in renal function, glucose and lipid profiles, and immune function indicators. These findings suggest that vitamin D may be a promising adjunctive agent for managing DN, but further prospective randomized controlled trials are needed to confirm causality.