Shyam Sunder Tummanapalli et al found that peripheral neuropathy, which is often the earliest sign of diabetes, could be traced in the tear film. Researchers found that people with type 1 diabetic peripheral neuropathy had reduced levels of a protein known as ‘substance P’ (SP) in their tear film. Scientists evaluated changes that occur in the concentrations of substance P and calcitonin gene-related peptide (CGRP) in tears as a result of corneal denervation. The experiment tested the concentration of these neuropeptides in the tear film of people with type 1 and type 2 diabetes compared to control groups. Participants with type 1 diabetes showed significantly reduced amounts SP peptide in their tear film, while CGRP remained unchanged. However, there was not any indication observed in type 2 diabetes. Researchers suggest that tear film protein SP may provide a potential non-invasive biomarker for assessing neuropathy in type 1 diabetic patients.
Source: The Ocular Surface 30 August 2019 DOI: 10.1016/j.jtos.2019.08.010 https://doi.org/10.1016/j.jtos.2019.08.010