NCT00992901 · The University of Texas Health Science Center at San Antonio
Role of Neural and Hormonal Regulation Factors on Insulin Secretion After Gastric Bypass Surgery
What this study is about
RYGB (roux-en-y gastric bypass) has been reported to reverse type 2 diabetes (T2DM) immediately after surgery before any significant weight loss. In addition, a growing number of patients have been recognized with life-threatening hyperinsulinemic hypoglycemia several years following their surgery.
View original scientific description
RYGB (roux-en-y gastric bypass) has been reported to reverse type 2 diabetes (T2DM) immediately after surgery before any significant weight loss. In addition, a growing number of patients have been recognized with life-threatening hyperinsulinemic hypoglycemia several years following their surgery. While the mechanisms by which RYGB improves glucose metabolism or alters islet cell function in patients after RYGB are not understood, recent studies suggest that increased secretion of GI hormones, primarily glucagon-like peptide 1 (GLP-1), as well as alteration in neural activity may contribute to enhanced insulin secretion in general, and to a greater extent in patients with hypoglycemia. The proposed research is designed to address the role of RYGB on insulin secretion by evaluating the contribution of stimulatory factors (neural and GI hormone) on islet cell function and the islet cell responsiveness to the physiologic stimulatory factors, in RYGB patients with and without hypoglycemia and non-operated controls.
Interventions
DRUG
Exendin-(9-39)
A physiological study to evaluate the role of GLP-1 signaling in glucose tolerance and insulin secretion
DRUG
Atropine
A physiological study to evaluate the effect of neural activation on insulin secretion and glucose metabolism
DRUG
GLP-1 and GIP
A physiological study to evaluate the beta-cell sensitivity to different doses of exogenous gut hormones
Primary outcome measures
Gut hormones and neural signaling contribution to insulin secretion rate and glucose tolerance
Time frame: Each study of the protocol is conducted up to seven hours with data collected at intervals specific to the individual study procedure.
Who can participate
This study lists these criteria on ClinicalTrials.gov. A study coordinator reviews eligibility during screening — this page does not determine whether you qualify.
Inclusion criteria
- Hypoglycemic RYGB patients with documented blood glucose level \<50 mg/dl
- Asymptomatic individuals with bariatric surgery
- Healthy non-surgical patients with no personal history of diabetes
- Subjects must physically be able to come to our clinical research center at Cedars-Sinai Medical Center
Exclusion criteria
- Active heart, lung, liver, gastrointestinal or kidney disease; unable to give informed consent; pregnancy; uncontrolled high blood pressure or high cholesterol; significant anemia (hemoglobin \<11g/dL); prisoners or institutionalized individuals; type 2 diabetes melitis; development of any serious medical or psychiatric illness during recruitment or studies;
- RYGB patients will also be disqualified if they have gastric outlet obstruction or severe diarrhea
- Healthy non-surgical patients with personal history of diabetes For administration of atropine, the following exclusions also apply:
- History of glaucoma
- Uncontrolled hypertension (any subjects with BP\>140/90 and history of dyslipidemia
- Taking any medication that might interact with atropine and cannot be stopped will be excluded from the study)
- Myasthenia gravis
- Brain pathology
- Enlarged prostate in men
Where
- San Antonio, Texas
Related conditions & keywords
Frequently asked questions
What is a clinical trial?
A clinical trial is a research study that tests new medical treatments, drugs, devices, or procedures to determine their safety and effectiveness. Trials are carefully designed and monitored to protect participants while advancing medical knowledge.
Is it safe to participate?
Clinical trials follow strict safety guidelines and ethical standards. Trials must be reviewed and approved, and participants are closely monitored by medical professionals throughout the study. You can withdraw at any time if you choose.
Will I be compensated?
Many clinical trials offer compensation for your time, travel expenses, and inconvenience. The specific compensation varies by study and will be discussed during the screening process. All study-related medical care is typically provided at no cost to participants.
Will I receive a placebo instead of treatment?
When effective treatment exists, participants typically receive either the standard treatment plus the study intervention, or the standard treatment plus placebo. You would not be denied effective care. Placebos are primarily used when no proven treatment is available, or in addition to standard care. Your trial consent form will clearly explain what treatments you may receive.
Can I leave a trial if I change my mind?
Absolutely. Participation in clinical trials is completely voluntary. You have the right to withdraw from the study at any time, for any reason, without penalty or loss of benefits to which you are otherwise entitled.
How long does a clinical trial last?
Trial duration varies widely depending on the study design and purpose. Some trials last just a few weeks, while others may continue for months or years. The study coordinator will provide specific timeline information during your screening call.
Data: ClinicalTrials.gov · synced Sep 9, 2025 · Source of record for eligibility and locations