Serum brain-derived neurotrophic factor, micronutrient status, and inflammatory cytokines in type 2 diabetes with nephropathy: a case-control analysis.

Background: Brain-derived neurotrophic factor (BDNF) levels are lower in diabetic patients compared to healthy individuals, and may be further affected by nephropathy. This study aimed to evaluate serum BDNF levels in diabetic patients with nephropathy without complications and compare them to levels in healthy control subjects. Methods: A case-control study was conducted involving three groups: healthy individuals (controls), diabetic patients without complications (DM), and diabetic nephropathy patients (DN). Serum BDNF levels were measured using the sandwich Enzyme-Linked Immunosorbent Assay (ELISA) technique, alongside serum levels of interleukin (IL)-12, IL-16, folic acid, vitamin B12, vitamin D3, total cholesterol, triglycerides, high density lipoprotein (HDL), hemoglobin A1c (HbA1c), urea, creatinine, total calcium, and zinc. Results: Serum BDNF levels were significantly lower in the DN group compared to the DM and control groups (42.1, 34.1, and 27.23 ng/mL, respectively). In the DM group, BDNF showed a direct correlation with HbA1c and urea (r = 0.26 and r = 0.35, respectively), and an inverse correlation with fasting plasma glucose (FPG) (r =  - 0.30). In the DN group, BDNF was directly correlated with FPG (r = 0.31) and serum creatinine (r = 0.27). The area under the curve (AUC) for BDNF in distinguishing DN from controls was 0.938, and 0.738 for DN versus DM. Conclusion: Serum BDNF levels are markedly reduced in type 2 diabetic patients with nephropathy and correlate with deficiencies in vitamins D, B12, folate, and zinc, as well as elevated IL-6 and IL-12. BDNF may serve as a biomarker for diabetic kidney disease, highlighting the importance of nutritional status, inflammation control, and neurotrophic support.