Brain-derived neurotrophic factor (BDNF) and other neurotrophic factors in type 2 diabetes mellitus and their association with neuropathy

Background: Diabetes mellitus (DM) is associated with increased risk of morbidity and premature mortality due to its various complications. In an Indian study, the prevalence of diabetic peripheral neuropathy (DPN) in type 2 diabetic subjects was shown to be 29.2%. There is increasing evidence that a deficiency of nerve growth factor (NGF) in diabetes, as well as the calcitonin gene-related peptide (CGRP), may also contribute to the development of DPN. The aim of the current study was to evaluate nerve growth factor levels with neuropathy in type 2 DM.

Materials and methods: Forty healthy controls and 40 patients with type 2 DM were recruited; they were asked to report to Dept. of Physiology for initial history taking, general examination and neuropathy examination. A total of 5 mL of blood was collected for neurotrophic factor estimation as well as glycemic profile estimation.

Results: The brain-derived neurotrophic factor (BDNF) values were significantly lower in the DM group whereas the insulin levels were also quite high in DM. The hot thresholds for both the upper limb and lower limb were greater in the DM group suggesting the impending neuropathy. Similarly, the Michigan scores were also greater in the DM group. The neuropathy parameters especially the Michigan A and B and the hot thresholds were positively correlated with duration of DM and glucose profile.

Conclusion: The neurotrophic factors especially BDNF are drastically reduced in DM patients and are negatively associated with neuropathy, and hence, BDNF can be utilized as a therapeutic target to treat and prevent neuropathy.