Relationship Between Changes in Gut Hormones After Gastric Bypass and Gastric Banding and Improvements in Diabetes
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The purpose of this study is to see how hormones that control blood sugar change in response to two different weight loss surgeries (gastric bypass and gastric banding). We believe that changes in a hormone called glucagon-like peptide-1 (GLP-1) may account for the greater improvement in blood sugar after certain types of surgeries. GLP-1 makes the pancreas release insulin, a hormone that lowers blood sugar. The study will consist of one screening visit and three study visits in which the glucose response will be measured after drinking a liquid meal: 1) Visit 1 (2-3 weeks before surgery); 2) Visit 2 (after 10% of body weight is lost); and 3) Visit 3 (5-10 days after Visit 2). Hormone levels will be measured during the three study visits. To see if the improvement in blood sugar after surgery is due to changes in GLP-1, we will block its effect on insulin release by giving either salt water or a medication that blocks the activity of GLP-1 during the two visits that take place after surgery (Visits 2 and 3).
Condition or disease
Type 2 DiabetesObesityBariatric Surgery
Many diabetic patients who have Roux-en-Y gastric bypass (RYGB) have rapid improvements in their blood sugars within days of their surgery, even before they have lost much weight. It typically takes much longer for these improvements to occur after adjustable gastric banding (AGB), despite an equally low caloric intake. Changes in levels of hormones released by the small intestine as a consequence of the particular type of surgery may be an important factor in the rapid improvement of blood sugars. One of these hormones, glucagon-like peptide-1 (GLP-1), has an important effect on insulin secretion from the pancreas. This study seeks to determine whether changes in GLP-1 are responsible for the improvement in blood sugar after certain types of weight loss surgeries. In order to meet inclusion criteria, participants must have type 2 diabetes for less than 10 years and be approved by insurance to undergo RYGB or AGB at the Hospital of the University of Pennsylvania or Penn Presbyterian Medical Center. We will obtain several measurements of GLP-1 and other hormones that affect glucose levels during the three study visits: 1) Visit 1 (2-3 weeks before surgery); 2) Visit 2 (after 10% of body weight is lost); and 3) Visit 3 (5-10 days after Visit 2). To see if the improvement in blood sugar after surgery is due to changes in GLP-1, we will block its effect on insulin release by giving either salt water or a medication that blocks the activity of GLP-1 during the two visits that take place after surgery (Visits 2 and 3). Each visit will last for 4-6 hours and participants will be compensated for their time.
change in glucose tolerance after surgery (measured by glucose area under the curve) [ Time Frame: after surgery when 10% of initial body weight is lost (expected 4 weeks after bypass and 12 weeks after banding) ]
To compare change in glucose tolerance, independent of weight loss, between obese, diabetic participants who undergo gastric bypass or gastric banding.
Secondary Outcome Measures
change in glucose tolerance before and after a GLP-1 receptor blocker is administered [ Time Frame: after 10% of body weight is lost (expected 4 weeks after bypass and 12 weeks after banding) ]
To determine if GLP-1 is responsible for improved glucose tolerance following gastric bypass.
Biospecimen Retention: Samples Without DNA
Extra blood will be stored for the potential analysis of additional hormones.
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Ages Eligible for Study:
18 Years and older (Adult, Senior)
Sexes Eligible for Study:
Accepts Healthy Volunteers:
Individuals with type 2 diabetes who are medically approved and have insurance approval to undergo gastric bypass or gastric banding at the University of Pennsylvania.
Male and female participants age 18 years or older with a body mass index greater than >35 kg/m2 but less than <60 kg/m2 who undergo gastric bypass or gastric banding at the University of Pennsylvania.
Type 2 diabetes (defined as a pre-existing diagnosis, the use of oral antidiabetic medications or insulin, or a fasting plasma glucose greater than or equal to > 126 mg/dl and confirmed by a oral glucose tolerance test)
Ability to provide written informed consent
A diagnosis of type 1 diabetes
Daily insulin requirement exceeding 1 unit/kg/d
Poor preoperative glycemic control, as indicated by an HbA1c greater than 10.0%
Duration of diabetes greater than> 10 years
Pregnant women (or those who intend to become pregnant during the study period)
Women who are currently breastfeeding
Participants with moderate anemia (hemoglobin less than< 12 g/dl for men and less than< 11 g/dl for women)
Use of medications known to affect weight, including chronic oral or inhaled glucocorticoid use and the use of certain psychiatric medications (olanzepine, risperidone, and lithium)
history of any major active rheumatologic, pulmonary, dermatologic disease, or inflammatory conditions
oral history of positive HIV status
any major surgery in the past 3 months
regular use of alcoholic beverages (greater than 7 drinks/week)