Effect of Gastric Electrical Stimulation on Serum Insulin Levels

Defining the Effect of Gastric Electrical Stimulation on Serum Insulin Levels in Human Subjects

The goal of this observational study is to determine how much effect turning the subject's Gastric Electrical Stimulator off for up to four hours will have on levels of insulin, C-peptide, GLP-1 and Glucose levels in patients with gastroparesis who have had a GES for at least three months, who are not taking diabetic prescribed exogenous insulin. EKG recordings will be made and analyzed for Heart Rate Variability and Power Spectral Analysis.

Study Overview

• Status: Recruiting
• Conditions: Gastroparesis Nondiabetic
• Intervention / Treatment: Device: Gastric Electrical Stimulator

Detailed Description

Up to thirty-two adult patients with gastroparesis who have undergone implantation of a gastric stimulation device at least three months prior are candidates for study. Diabetic patients who are taking exogenous insulin are excluded from study The study consists of two groups, an EXPERIMENTAL group that undergoes turning off the GES and a CONTROL group that does not undergo the turning off of the GES. The subjects are randomized to either the control or experimental group. The study Coordinator will create a block randomization schedule in Excel (Block Randomization in Clinical Trials: Video Tutorial in Microsoft Excel)(10). The study Coordinator will use the Excel randomization schedule to assign the treatment and will administer the stimulus accordingly. No one will be blinded to any of the arms of the study.

After an overnight fast, the patients are placed in the supine position on a hospital bed, and an intravenous line is inserted and capped. The study consists of three separate and consecutive periods: 1. Baseline, a 20-minute period during which GES is left ON at each patient's pre-study settings; 2. Experimental, a 4-hour period during which the GES device is turned OFF; 3. Recovery, a 20-minute period during which GES is turned back ON to the patient's pre-study settings. A 5-ml sample of blood will be removed from each patient after placement of the flexible IV catheter secured with tape, the Baseline, and Recovery study periods. During the Experimental period a blood sample is withdrawn after 30 minutes and then again at the 1-hour, 2-hour, 3-hour and 4-hour intervals through a flexible IV catheter secured with tape , with the possibility of up to 8 blood draws over the duration of the study.

Plasma samples are analyzed for glucose, C-peptide, GLP-1 and insulin levels. The analysis of variance is used to determine whether there is any significant effect of time on the resultant values. In a previous study we examined the variance of patient demographics (age, gender, and BMI). As patients with implanted electrical stimulators typically have different stimulator settings to control their symptoms, this arm of the study examines whether stimulation parameters such as pulse duration, amplitude or frequency have any effect on individual response to gastric electrical stimulation. A correlation coefficient analysis is used to determine if any variable shows a significant effect.

During the study EKG electrodes are placed over the extremities and precordium and recordings continued during the respective Baseline, Experimental, and Recovery periods. EKG signals are digitized and downloaded to a computer for time domain power spectral analysis of heart rate variability using commercially available software. This analysis will determine the influence of sympathetic and parasympathetic mechanisms during the respective time periods.

• Study Type: Interventional
• Enrollment (Estimated): 32
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Thomas V Nowak, MD; Phone Number: 3179484272; Email: tvnowak@iu.edu
• Study Contact Backup: Name: Maureen V Schilling, BA; Phone Number: 3172782064; Email: maschi@iu.edu

Study Locations

• United States
  • Indiana
    • Indianapolis, Indiana, United States, 46202
      • Recruiting
      • Indiana University Hospital
      • Contact: Thomas V Nowak, MD; Phone Number: 3179484272; Email: tvnowak@iu.edu
      • Contact: Maureen Schilling, BA; Phone Number: 317-278-2064; Email: maschi@iu.edu

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• • At least 18 years of age.

  • Documented diagnosis of gastroparesis
  • Not taking diabetic prescribed exogenous insulin.
  • Patient has a GES device that has been implanted for at least 3 months.
  • Willing to give up to 8 blood samples.
  • Willing to lie in a bed for up to 5.5 hours.

Exclusion Criteria:

• • Pregnancy

  • History of allergic reaction to EKG lead placement adhesives.
  • Unable to give informed consent.
  • Unwilling to give up to 8 5 ml blood samples.
  • Unwilling to lie in a bed for up to 5.5 hours.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Health Services Research
• Allocation: Randomized
• Interventional Model: Single Group Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: The OFF Group; This group of subjects will have their GES interrogated and observed as well as having the device turned off for the duration of the experiment. The device will then be re-interrogated and turned back on at the end of the experiment.	Device: Gastric Electrical Stimulator; Device will either be turned off for the duration of the experiment, or the device will be left on for the duration of the experiment; Other Names: GES
Sham Comparator: SHAM Group; This group of subjects will have their GES interrogated and observed yet will not have the device turned off for the duration of the experiment. The device will then be re-interrogated at the end of the experiment. This is to retain the illusion of the device being turned back on.	Device: Gastric Electrical Stimulator; Device will either be turned off for the duration of the experiment, or the device will be left on for the duration of the experiment; Other Names: GES

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Definition of Effect	To define the effect of prolonged four-hour withdrawal of gastric electrical stimulation on serum insulin and C-peptide levels in human subjects. Insulin and C-peptide are co-primary end points.	Up to four hours depending on the subject's preference/tolerability.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Comparing Hormone Levels	To compare the changes in serum insulin and C-peptide levels after 4-hour withdrawal of gastric electrical stimulation to a control group that does not undergo withdrawal of gastric electrical stimulation.	Up to four hours depending on the subject's preference/tolerability.
Definition of 4-Hour Withdrawl of GES Device	To define the effect of prolonged four-hour withdrawal of gastric electrical stimulation on serum GLP-1 and glucose levels in human subjects. GLP-1 and glucose are co-secondary end points.	Up to four hours depending on the subject's preference/tolerability.
Changes in Glucose and GLP-1 Levels	To compare the changes in serum GLP-1 and glucose levels after 4-hour withdrawal of gastric electrical stimulation to a control group that does not undergo withdrawal of gastric electrical stimulation.	Up to four hours depending on the subject's preference/tolerability.

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Tertiary Objective	To determine whether changes noted in serum levels of insulin, C-peptide, GLP-1 and glucose are associated with alterations in heart rate variability and sympathetic and parasympathetic autonomic activation.	Up to four hours depending on the subject's preference/tolerability.

Collaborators and Investigators

• Sponsor: Indiana University
• Investigators: Principal Investigator: Thomas V Nowak, MD, IU School of Medicine/IU Health

Publications and helpful links

General Publications

• van der Voort IR, Becker JC, Dietl KH, Konturek JW, Domschke W, Pohle T. Gastric electrical stimulation results in improved metabolic control in diabetic patients suffering from gastroparesis. Exp Clin Endocrinol Diabetes. 2005 Jan;113(1):38-42. doi: 10.1055/s-2004-830525.
• Vosseler A, Zhao D, Fritsche L, Lehmann R, Kantartzis K, Small DM, Peter A, Haring HU, Birkenfeld AL, Fritsche A, Wagner R, Preissl H, Kullmann S, Heni M. No modulation of postprandial metabolism by transcutaneous auricular vagus nerve stimulation: a cross-over study in 15 healthy men. Sci Rep. 2020 Nov 24;10(1):20466. doi: 10.1038/s41598-020-77430-2.
• Kozorosky EM, Lee CH, Lee JG, Nunez Martinez V, Padayachee LE, Stauss HM. Transcutaneous auricular vagus nerve stimulation augments postprandial inhibition of ghrelin. Physiol Rep. 2022 Apr;10(8):e15253. doi: 10.14814/phy2.15253.
• Payne SC, Ward G, Fallon JB, Hyakumura T, Prins JB, Andrikopoulos S, MacIsaac RJ, Villalobos J. Blood glucose modulation and safety of efferent vagus nerve stimulation in a type 2 diabetic rat model. Physiol Rep. 2022 Apr;10(8):e15257. doi: 10.14814/phy2.15257.
• Hampton RF, Jimenez-Gonzalez M, Stanley SA. Unravelling innervation of pancreatic islets. Diabetologia. 2022 Jul;65(7):1069-1084. doi: 10.1007/s00125-022-05691-9. Epub 2022 Mar 29.

Helpful Links

• Block Randomization in Clinical Trials: Video Tutorial in Microsoft Excel

Study record dates

Study Major Dates

• Study Start (Estimated): June 8, 2026
• Primary Completion (Estimated): July 31, 2028
• Study Completion (Estimated): September 30, 2030

Study Registration Dates

• First Submitted: June 3, 2026
• First Submitted That Met QC Criteria: June 3, 2026
• First Posted (Actual): June 9, 2026

Study Record Updates

• Last Update Posted (Actual): June 9, 2026
• Last Update Submitted That Met QC Criteria: June 3, 2026
• Last Verified: June 1, 2026

More Information

Terms related to this study

• Other Study ID Numbers: 30020 (DAIDS-ES Registry Number)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: Yes
• product manufactured in and exported from the U.S.: Yes