Pre-diabetes
Conditions
Keywords
Blood sugar, GIP, Xenin-25, Cholinergic Signaling, Atropine, Insulin, Glucagon, Pancreatic polypeptide
Brief summary
Glucose-dependent insulinotropic polypeptide (GIP) is a hormone produced in the intestine. It is released immediately after meal ingestion and increases insulin release. This, in turn, helps reduce blood glucose levels. This circuit does not work properly in humans with type 2 diabetes mellitus (T2DM). We have previously shown that a peptide called xenin-25 can amplify the effects of GIP on insulin secretion in humans. However, xenin-25 no longer does this when humans develop T2DM. Thus, it is important to understand how xenin-25 works in humans without T2DM so we know why it does not work in humans with T2DM. Acetylcholine is molecule produced by specific types of nerves. The effects of acetylcholine can be blocked by a drug called atropine. We have previously shown in mice that atropine prevents the ability of xenin-25 to increase the effects of GIP on insulin release. The purpose of this clinical trial is to determine if atropine also blocks the effects of xenin-25 in humans without T2DM. If it does, then impaired acetylcholine signaling may be one of the reasons humans develop T2DM and it could be possible to develop drugs that bypass this defect and increase insulin release in humans with T2DM.
Detailed description
Glucose-dependent insulinotropic polypeptide (GIP) is a hormone produced in the intestine. It is released immediately after meal ingestion and increases insulin release. This, in turn, helps reduce blood glucose levels. This circuit does not work properly in humans with type 2 diabetes mellitus (T2DM). We have previously shown that a peptide called xenin-25 can amplify the effects of GIP on insulin secretion in humans. However, xenin-25 no longer does this when humans develop T2DM. Thus, it is important to understand how xenin-25 works in humans without T2DM so we know why it does not work in humans with T2DM. Acetylcholine is molecule produced by specific types of nerves. The effects of acetylcholine can be blocked by a drug called atropine. We have previously shown in mice that atropine prevents the ability of xenin-25 to increase the effects of GIP on insulin release. The purpose of this clinical trial is to determine if atropine also blocks the effects of xenin-25 in humans without T2DM. If it does, then impaired acetylcholine signaling may be one of the reasons humans develop T2DM and it may be possible to develop drugs that bypass this defect and increase insulin release in humans with T2DM. To conduct this study, we will enroll humans with pre-diabetes since they respond very well to xenin-25. Potential subjects will first be checked to see if they do have pre-diabetes and also to verify that they can safely participate in the study. Once enrolled, subjects will come for 8 different visits, each separated by about 3 weeks. On each visit, the subject will be given an intravenous infusion of glucose such that blood glucose levels slowly increase over a 4 hour period. On separate occasions, the participant will also receive an infusion GIP alone, xenin-25 alone, GIP plus xenin-25, or placebo. Each of these 4 infusions will be conducted with and without an infusion of atropine (thus- the 8 visits). Blood glucose and insulin levels, as well as a host of other hormones, will be measured during each of the study visits. A comparison of the results will tell us if the effects of xenin-25 on insulin release are mediated by acetylcholine in humans.
Interventions
DRUGControl
Starting at 0 minutes, glucose infusion rates will be increased to 1, 2, 3, 4, 6, and 8 mg/kg/min every 40 minutes. The study is finished at 240 minutes. Starting at 0 minutes, an intravenous infusion of saline containing 1% human albumin will continue for 240 minutes.
DRUGXenin-25 without atropine
Starting at 0 minutes, glucose infusion rates will be increased to 1, 2, 3, 4, 6, and 8 mg/kg/min every 40 minutes. The study is finished at 240 minutes. Following a priming dose from 0-10 minutes, xenin-25 (in saline containing 1% human albumin) will be administered at a constant dose of 4 pmoles/kg/min until 240 minutes.
DRUGGIP without atropine
Starting at 0 minutes, glucose infusion rates will be increased to 1, 2, 3, 4, 6, and 8 mg/kg/min every 40 minutes. The study is finished at 240 minutes. Following a priming dose from 0-10 minutes, GIP (in saline containing 1% human albumin) will be administered at a dose of 4 pmoles/kg/min until 240 minutes.
DRUGPlacebo with atropine
Starting at 0 minutes, glucose infusion rates will be increased to 1, 2, 3, 4, 6, and 8 mg/kg/min every 40 minutes. The study is finished at 240 minutes. Following a priming dose from -30 to -28 minutes, atropine will be administered at a constant dose of 0.3 mg/m2/hour until 240 minutes.
DRUGXenin-25 with atropine
Starting at 0 minutes, glucose infusion rates will be increased to 1, 2, 3, 4, 6, and 8 mg/kg/min every 40 minutes. The study is finished at 240 minutes. Following a priming dose from 0-10 minutes, xenin-25 (in saline containing 1% human albumin) will be administered at a dose of 4 pmoles/kg/min until 240 minutes. Following a priming dose from -30 to -28 minutes, atropine will be administered at a constant dose of 0.3 mg/m2/hour until 240 minutes.
DRUGGIP with atropine
Starting at 0 minutes, glucose infusion rates will be increased to 1, 2, 3, 4, 6, and 8 mg/kg/min every 40 minutes. The study is finished at 240 minutes. Following a priming dose from 0-10 minutes, GIP (iin saline containing 1% human albumin) will be administered at a dose of 4 pmoles/kg/min until 240 minutes. Following a priming dose from -30 to -28 minutes, atropine will be administered at a constant dose of 0.3 mg/m2/hour until 240 minutes.
DRUGGIP plus Xenin-25 without atropine
Starting at 0 minutes, glucose infusion rates will be increased to 1, 2, 3, 4, 6, and 8 mg/kg/min every 40 minutes. The study is finished at 240 minutes. Following a priming dose from 0-10 minutes, GIP and xenin-25 will each be administered at a dose of 4 pmoles/kg/min until 240 minutes.
DRUGGIP plus Xenin-25 with atropine
Starting at 0 minutes, glucose infusion rates will be increased to 1, 2, 3, 4, 6, and 8 mg/kg/min every 40 minutes. The study is finished at 240 minutes. Following a priming dose from 0-10 minutes, GIP and xenin-25 will each be administered at a dose of 4 pmoles/kg/min until 240 minutes. Following a priming dose from -30 to -28 minutes, atropine will be administered at a constant dose of 0.3 mg/m2/hour until 240 minutes.
Sponsors
American Diabetes Association
Washington University School of Medicine
Study design
Allocation
NA
Intervention model
SINGLE_GROUP
Primary purpose
BASIC_SCIENCE
Masking
SINGLE (Subject)
Eligibility
Sex/Gender
ALL
Age
18 Years to 65 Years
Healthy volunteers
Yes
Inclusion criteria
* Individuals must be able to consent for their own participation (no mental impairment affecting cognition or willingness to follow study instructions). * Otherwise healthy volunteers that have borderline diabetes or impaired glucose tolerance. * Women of childbearing potential must be currently taking/using an acceptable method of birth control. A pregnancy test will be done at the beginning of each visit. Any woman with a positive pregnancy test will be removed from the study. * Willingness to complete all required visits.
Exclusion criteria
* Lacks cognitive ability to sign the consent or follow the study directions. * Women unwilling to use an acceptable method of contraception during the course of the study, or who are currently breast-feeding. * Volunteers with a history of Acute Pancreatitis. * Volunteers with a history of cancer (except for skin cancer). * Volunteer with a history of Chronic Pancreatitis and/or risk factors for chronic pancreatitis including hypertriglyceridemia, hypercalcemia and/or the presence of gallstones. * Volunteers with a history of gastrointestinal disorders, particularly related to gastric motility/emptying such as gastric bypass * Subjects taking medications known to affect glucose tolerance. * Anemia * Significant systemic illness including heart, kidney, inflammatory, liver, or malignant disease requiring medications. * Narrow-angle glaucoma * Obstructive uropathy including benign prostatic hypertrophy, pyloric stenosis, myasthenia gravis * Asthma * hyperthyroidism * angina and cardiac arrhythmias including heart block * Subjects unwilling to allow the use of human albumin in the preparation of the peptides. * Unwillingness to allow blood glucose level adjustment (if needed) with IV insulin
Design outcomes
Primary
| Measure | Time frame |
|---|---|
| Insulin secretion rates during each treatment. | 3 years |
Secondary
| Measure | Time frame |
|---|---|
| Plasma glucose levels during each treatment. | 3 years |
| Plasma glucagon levels during each treatment. | 3 years |
| Plasma pancreatic polypeptide levels during each treatment. | 3 years |
Other
| Measure | Time frame |
|---|---|
| Plasma GIP levels during each treatment | 3 years |
| Plasma xenin-25 levels during each treatment. | 3 years |
Countries
United States
Outcome results
None listed