Endocrine and metabolic results. (A) Blood glucose, (B) serum insulin and (C) C-peptide increases during the oral glucose tolerance test (OGTT) that started at 0 min. Plasma adrenaline (D) and noradrenaline (E) decreased. However, transcutaneous vagus nerve stimulation (taVNS) did not significantly influence any of the hormone levels. Presented are means, error bars indicate standard errors.