Effect of Gastric Electrical Stimulation on Serum Insulin Levels

Up to thirty‐two adult patients with gastroparesis who have undergone implantation of agastric stimulation device at least three months prior are candidates for study. Diabeticpatients who are taking exogenous insulin are excluded from study The study consists oftwo groups, an EXPERIMENTAL group that undergoes turning off the GES and a CONTROL groupthat does not undergo the turning off of the GES. The subjects are randomized to eitherthe control or experimental group. The study Coordinator will create a blockrandomization schedule in Excel (Block Randomization in Clinical Trials: Video Tutorialin Microsoft Excel)(10). The study Coordinator will use the Excel randomization scheduleto assign the treatment and will administer the stimulus accordingly. No one will beblinded to any of the arms of the study.After an overnight fast, the patients are placed in the supine position on a hospitalbed, and an intravenous line is inserted and capped. The study consists of three separateand consecutive periods: 1. Baseline, a 20‐minute period during which GES is left ON ateach patient's pre‐study settings; 2. Experimental, a 4‐hour period during which the GESdevice is turned OFF; 3. Recovery, a 20‐minute period during which GES is turned back ONto the patient's pre‐study settings. A 5‐ml sample of blood will be removed from eachpatient after placement of the flexible IV catheter secured with tape, the Baseline, andRecovery study periods. During the Experimental period a blood sample is withdrawn after30 minutes and then again at the 1‐hour, 2‐hour, 3‐hour and 4‐hour intervals through aflexible IV catheter secured with tape , with the possibility of up to 8 blood draws overthe duration of the study.Plasma samples are analyzed for glucose, C‐peptide, GLP‐1 and insulin levels. Theanalysis of variance is used to determine whether there is any significant effect of timeon the resultant values. In a previous study we examined the variance of patientdemographics (age, gender, and BMI). As patients with implanted electrical stimulatorstypically have different stimulator settings to control their symptoms, this arm of thestudy examines whether stimulation parameters such as pulse duration, amplitude orfrequency have any effect on individual response to gastric electrical stimulation. Acorrelation coefficient analysis is used to determine if any variable shows a significanteffect.During the study EKG electrodes are placed over the extremities and precordium andrecordings continued during the respective Baseline, Experimental, and Recovery periods.EKG signals are digitized and downloaded to a computer for time domain power spectralanalysis of heart rate variability using commercially available software. This analysiswill determine the influence of sympathetic and parasympathetic mechanisms during therespective time periods.