Two important mechanisms play a major role in the pathogenesis of type 2 diabetes: insulin resistance of the target tissues and the impaired insulin secretion from pancreatic β-cells. Postprandial factors (such as insulin) are perceived by the human brain and induce signals that regulate glucose metabolism via the parasympathetic nervous system.

Transcutaneous auricular vagus nerve stimulation (tVNS) can be used on the outer ear to stimulate the auricular branch of the vagus nerve in humans. Heart rate variability (HRV) in healthy people can be significantly increased via tVNS, indicating a shift from sympathetic activity to parasympathetic activity.

The hypothesis is that this postprandial shift results in a change in peripheral glucose metabolism. In turn, the increased parasympathetic activity could potentially result in a change in postprandial insulin sensitivity or secretion.

To test this hypothesis, this study investigates the effect of vagal stimulation versus sham stimulation on insulin sensitivity, on insulin secretion, glucose tolerance, resting energy expenditure, and on parasympathetic tone (analysis of heart rate variability).

Inclusion Criteria:

• HbA1c <6.5%
• Must be able to understand the explanations of the study and the instructions

Exclusion Criteria:

• Any relevant (according to investigator's judgment) cardiovascular disease
• Neurological and psychiatric disorders
• Diabetes mellitus
• Active implants (e.g. pacemaker, cochlear implant, cerebral shunt)
• asthma
• skin diseases on the ear

Due to ethical restrains, we will not be able to share patient level data.