Transcutaneous vagus nerve stimulation does not affect gastrointestinal function in subjects with diabetic autonomic neuropathy

BACKGROUND AND AIMS: Transcutaneous vagus nerve stimulation has been suggested to alleviate gastrointestinal symptoms in subjects with diabetic autonomic neuropathy. This study aimed to examine the effect of this treatment on magnetic resonance imaging (MRI)-assessed gastrointestinal function. METHODS: This study included data from a randomized, sham-controlled, double-blind parallel group trial. Subjects with type 1 or 2 diabetes with manifest gastrointestinal symptoms and diabetic autonomic neuropathy were included. Subjects were randomized to one week of active or sham transcutaneous vagus nerve stimulation. A meal-stimulated pan-alimentary MRI scan protocol was performed after the one week stimulation. Gastric, small bowel, and colonic volumes were assessed, as were gastric half-emptying time, small bowel motility, and gastrointestinal symptom scores. KEY RESULTS: Thirty-four patients were included. Eighteen and sixteen patients were randomized to active and sham treatment, respectively. Gastric, small bowel, and colonic volumes were not different between treatment groups at any post-meal time points after one week of treatment (all p > 0.80). Gastric half-emptying time was not different between active and sham groups (105+/-37 min vs. 101+/-36 min, p = 0.77). Small bowel motility 105 min postprandially was higher in the active group compared to sham (184 ± 53 au. vs. 138+/-28 au., p = 0.04), whereas none of the remaining time points showed any differences (all p > 0.47). Symptom scores were unaffected by treatment (all p > 0.51), and no correlations between symptom scores and MRI measurements were found (all p > 0.16). CONCLUSIONS: Transcutaneous vagus nerve stimulation did not affect MRI-assessed gastrointestinal function in subjects with diabetic autonomic neuropathy.