Evaluation of the Effect of Cocoa Supplementation on Biochemical and Clinical Profile and Sensory-motor Processing of Peripheral and Autonomic Diabetic Neuropathy: Randomized Clinical Trial

Type 2 diabetes mellitus (T2DM) is a high incidence disease in Mexico and is associated with the development of chronic degenerative complications such as diabetic neuropathy. The latter manifests itself as a set of disorders that occur as a consequence of a chronic hyperglycemic state that can induce oxidative stress and inflammation, resulting in damage to the autonomic and peripheral nervous system. In Mexico, it has been reported that this complication usually occurs between 29% and 90% of patients with diabetes.

Cocoa is a food with a high content of flavonoids, which are phenolic compounds with antioxidant and anti-inflammatory effects. Additionally, its consumption has been associated with a decrease in hyperglycemia and insulin resistance, improvement in mitochondrial function, and, based on the above, an effect on diabetic complications has been suggested; This has been demonstrated in in vivo and in vitro models, but not in the human population.

Once the symptoms of diabetic neuropathy have started, palliative treatments are prescribed, and to date there are no pharmacological compounds that have been shown to reverse the consequences of diabetic peripheral and autonomic neuropathy. Additionally, clinical trials of compounds with antioxidant properties have only performed subjective evaluations based on questionnaires on the perception of the improvement of diabetic neuropathy and some biochemical markers or nerve conduction tests, however, the results shown have not been conclusive.

This is why a double-blind, randomized controlled clinical trial is proposed, with the objective of evaluating the effect of cocoa supplementation in patients with type 2 diabetes mellitus and peripheral and autonomic diabetic neuropathy on a) the biochemical profile, which includes the evaluation of the glycemic and lipid profile, quantification of pro-inflammatory cytokines and oxidative stress markers; b) the clinical profile through the application of standardized questionnaires, anthropometric measurements and blood pressure, and c) somatosensory processing through the paired pulse H reflex test. Hypothesis: The hypothesis of this study is that cocoa supplementation will have a beneficial effect on the biochemical and clinical profile and somatosensory processing of peripheral and autonomic diabetic neuropathy. Statistical analysis: For the evaluation of the intragroup variables, a statistical analysis will be carried out with ANOVA for repeated samples with Tukey's post hoc, or, where appropriate, Friedman with Dunn's post hoc, as well as Student's t for dependent groups, or in its case, with Wilcoxon. The intergroup comparison will be made with Student's T for independent samples, or if applicable, with Mann Whitney's U, considering p <0.05 as statistical significance and using the statistical software GraphPad Prism version 5.

The H reflex test will be performed by electrical stimulation through disposable surface electrodes connected to a constant current bipolar electrical stimulator (Digitimer DS8R). The recording of the electrophysiological signals will be carried out using surface electrodes connected to the signal acquisition and amplification system (LabChart and PowerLab 8/35, ADInstruments). The signals obtained will be sampled at 10 kilohertz (KHz) with a 0.5- 500 Hz band-pass filter. The signals will be stored in a computer for later analysis.