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).
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
SINGLE
Enrollment
15
Stimulation will be performed for 150 minutes (throughout the entire OGTT).
Sham stimulation will be performed for 150 minutes (throughout the entire OGTT)
University of Tuebingen, Department of Internal Medicine IV
Tübingen, Germany
Whole body insulin sensitivity
Insulin sensitivity will be assessed by a 75g OGTT.
Time frame: 0-120 min
Insulin secretion
Insulin secretion will be assessed by a 75g OGTT
Time frame: 0-120 min
Glucose tolerance
Glucose tolerance will be assessed by a 75g OGTT
Time frame: 0-120 min
Resting energy expenditure
Resting energy expenditure will be assessed by indirect calorimetry
Time frame: 140-160 min. after start of stimulation
Heart rate variability
Heart rate variability will be assessed from continuous ecg recordings
Time frame: -30 - 120 min
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