The purpose of this study is to evaluate the mechanisms leading to rapid postoperative improvement in diabetes following Gastric By-Pass surgery for obesity.We will evaluate and compare the changes in glucose level, beta-cell function, and insulin resistance induced by a week of very low calorie liquid diet and those induced by a week of matched very -low calorie liquid diet occuring in the context of routine postoperative care following RYGB.
Volunteers planned to undergo RYGB will be studied during two-9 days periods of identical and controlled diet and activity, separated by a 4-10-week washout period. Study Period #1: This first study period is 9 days/nights long and requires you to be closely supervised at our Clinical and Translational Research Center (CTRC). During this time you will receive the same diet and are expected to have the same activity level you will be prescribed in the immediate post-operative period. Wash-out period: During this study period you are expected to return to your usual diet and exercise level. Study Period #2: This last study period is also 9 days/nights long, includes the EXACT same diet you have received during the first study period, and in addition you will undergo the planned gastric by-pass surgery. Procedures during the research: Mixed Meal Challenge test will be done four times during the entire study: days 1 and 9 for each study period. This test allows the investigators to evaluate how much insulin your body is producing and how well this insulin is processed. Measurement of resting energy expenditure will be done four times during the entire study. This test tell us how much energy your body is burning up in a resting state.
Study Type
OBSERVATIONAL
Enrollment
22
Clinical and Translational Research Center
Dallas, Texas, United States
Response in Glucose AUC at Baseline vs. Following Gastric Bypass Surgery
Changes in the glucose Area Under the Curve (AUC) calculated as the difference between the initial evaluation (test 1, assessed at day 1) and the next evaluation (test 2, assessed at day 9) of study period 1. Subjects then underwent gastric bypass surgery approximately 4-10 weeks later. In study period 2 following surgery, changes in the glucose AUC was again calculated as the difference between the initial evaluation (test 3, assessed at day 1 following surgery) and the next evaluation (test 4, assessed at day 9 following surgery). Change in AUC in study period 1 was compared to change in AUC in study period 2. Blood samples were collected at 5, 10, 15, 20, 25, 30, 40, 50, 60, 80, 100, 120, 150, 180, 210, 240, 300, and 360 minutes after the ingestion of 240 mL of chocolate Boost Plus Nestle. Total AUC was computed using the trapezoidal rule.
Time frame: 4-12 weeks
Response in Insulin AUC at Baseline vs Following Gastric Bypass Surgery
Changes in the Insulin Area Under the Curve (AUC) calculated as the difference between the initial evaluation (test 1, assessed at day 1) and the next evaluation (test 2, assessed at day 9) of study period 1. Subjects then underwent gastric bypass surgery approximately 4-10 weeks later. In study period 2 following surgery, changes in the insulin AUC was again calculated as the difference between the initial evaluation (test 3, assessed at day 1 following surgery) and the next evaluation (test 4, assessed at day 9 following surgery). Change in AUC in study period 1 was compared to change in AUC in study period 2. Blood samples were collected at 5, 10, 15, 20, 25, 30, 40, 50, 60, 80, 100, 120, 150, 180, 210, 240, 300, and 360 minutes after the ingestion of 240 mL of chocolate Boost Plus Nestle. Total AUC was computed using the trapezoidal rule.
Time frame: 4-12 weeks
Response in Glucagon AUC at Baseline vs. Following Gastric Bypass
Changes in the glucagon Area Under the Curve (AUC) calculated as the difference between the initial evaluation (test 1, assessed at day 1) and the next evaluation (test 2, assessed at day 9) of study period 1. Subjects then underwent gastric bypass surgery approximately 4-10 weeks later. In study period 2 following surgery, changes in the glucagon AUC was again calculated as the difference between the initial evaluation (test 3, assessed at day 1 following surgery) and the next evaluation (test 4, assessed at day 9 following surgery). Change in AUC in study period 1 was compared to change in AUC in study period 2. Blood samples were collected at 5, 10, 15, 20, 25, 30, 40, 50, 60, 80, 100, 120, 150, 180, 210, 240, 300, and 360 minutes after the ingestion of 240 mL of chocolate Boost Plus Nestle. Total AUC was computed using the trapezoidal rule.
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Time frame: 4-12 weeks