Correlation between vitamin D and serum brain derived neurotropic factor levels in type 2 diabetes mellitus patients

Diabetes Mellitus (DM) currently ranks as the most common endocrine disorder worldwide. Current opinion views DM as a group of heterogeneous metabolic diseases characterized by hyperglycemia triggered by defects in the ability of the body to produce or use insulin in type 1 and 2 DM, respectively. Brain-derived neurotrophic factor (BDNF), one of the neurotrophin family of growth factors, has been linked to the pathogenesis of DM and insulin resistance. Moreover, vitamin D has been associated with insulin resistance and DM. Recently, the interactions between vitamin D and BDNF have been investigated in diabetic rats. However, this correlation has never been investigated in humans. Thus, the aim of the present study was to assess the alterations in serum BDNF and vitamin D levels in T2DM patients in Jordan, prior to and following vitamin D supplementation. A combination of non-experimental case-control and experimental designed studies were utilized to assess the relationship between serum BDNF and vitamin D levels in T2DM patients. The levels of BDNF and vitamin D were measured using commercially available ELISA kits, and fasting blood glucose (FBG) and HbA1c levels were measured in medical labs. The results showed that diabetic patients had lower levels of serum vitamin D and higher levels of BDNF compared with the healthy controls. Moreover, linear regression analysis indicated that BDNF levels were inversely correlated with serum vitamin D levels. Furthermore, vitamin D supplementation significantly increased vitamin D serum levels and decreased BDNF serum levels in diabetic patients. Intriguingly, FBG and HbA1c levels were significantly improved post vitamin D supplementation. These data demonstrate a positive effect of vitamin D supplementation in diabetic patients suggesting the implementation of vitamin D as part of future T2DM treatment plans. However, additional studies are needed to investigate the direct link between vitamin D, BDNF, and T2DM.