A Pilot Study to Evaluate the Glucagon-Like Peptide 1 Response to the Challenge of Mixed Meals in Chinese Subjects

Study Overview
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Brief Summary
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The purpose of the study is to standardize a meal test to facilitate future studies of the postprandial glucagons-like peptide 1 (GLP-1) response in Chinese subjects. Eighteen healthy Chinese subjects, aged between 20-65 years old, without history of diabetes, will be recruited for the study. Each subject will receive two mixed meal tests for postprandial GLP-1 excursion at random order: 60 % carbohydrate (CHO)/20 % fat vs. 50 % CHO/30 % fat. The postprandial glucose, insulin, glucagon and other related hormones responses will also be measured. Through the study, we hope to build up a platform for the study of the postprandial GLP-1 response and insulin secretion.

Detailed Description
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Glucagon-like peptide 1 (GLP-1) is a 30-amino acid peptide produced in the intestinal epithelial endocrine L-cells. It stimulates insulin and suppresses glucagons secretion, inhibits gastric emptying, and reduces appetite and food intake. In the fasting state, the plasma concentrations of GLP-1 are very low. Levels of circulating GLP-1 rise rapidly after food intake. The GLP-1 meal response depends on ingested nutrients. Carbohydrates are strong stimuli of GLP-1 release. Protein stimulates GLP-1 release, even more than carbohydrates. GLP-1 concentrations also increase after intake of fat, although the elevation is delayed compared to the stimulation of carbohydrates. Dietary fibers may also modify the postprandial GLP-1 response. Therefore, it is essential for us to characterize nutrient compositions of test meals for further studies of meal response of GLP-1. Other sampling conditions of the meal tests are also needed to be taking care of. GLP-1 is rapidly degraded by the enzyme dipeptidyl peptidase IV (DPP-4). During the meal tests, it is important adding enzyme inhibitors into sampling tubes to avoid hormone degradation. Lugari et al. collected blood samples into tubes containing EDTA and aprotinin during a meal test. They could obtain samples from the same tube for both glucagons and GLP-1 assays. Other study groups reported that samples for GLP-1 needed to be collected into Vacutainer tubes prepared with EDTA and DPP-4 inhibitor for preventing degradation of GLP-1. Another aim of the present study is to compare the differences in GLP-1 concentrations in samples collected by EDTA tubes containing aprotinin or a DPP-4 inhibitor during the meal tests. Racial differences in GLP-1 levels during oral glucose challenge have been demonstrated recently that severely obese African Americans exhibited lower GLP-1 concentrations than Caucasians. It is worthwhile to examine the meal response of GLP-1 across ethnicities. The current study proposes to observe the GLP-1 response during standardized meal tests in a group of Chinese subjects. The purpose of the study is to standardize a meal test to facilitate future studies of the postprandial GLP-1 response in Chinese subjects. Eighteen healthy Chinese subjects, aged between 20-65 years old, without history of diabetes, will be recruited for the study. Each subject will receive two mixed meal tests for postprandial GLP-1 excursion at random order: 60 % carbohydrate (CHO)/20 % fat vs. 50 % CHO/30 % fat. The postprandial glucose, insulin, glucagon and other related hormones responses will also be measured. Through the study, we hope to build up a platform for the study of the postprandial GLP-1 response and insulin secretion.

Official Title
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A Pilot Study to Evaluate the Glucagon-Like Peptide 1 Response to the Challenge of Mixed Meals in Chinese Subjects

Conditions
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Healthy

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Men or women aged 20   65 years old. Willing to participate by signing an informed consent. Willing to undergo two standardized mixed meal test at two separate visits Exclusion Criteria: Patients of known history of type 2 diabetes. History of major renal, liver, heart, blood and neurological disease. History of alcoholism or drug abuse. Women who are pregnant. Current or concomitant illness that would interfere with the subject's ability to perform the study or that would confound the study results, judged by the investigation physicians. Any concomitant medication within 2 weeks of the study. Difficult venous access

Ages Eligible for Study
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Minimum Age: 20 Years
Maximum Age: 65 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Healthy Adults<br>Chinese in origin Healthy No medication at least two weeks before the study | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| the differences in post-challenge GLP-1 responses between the two meal tests |  | 8 months | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| the correlations of incremental GLP-1 response with insulin sensitivity and insulin secretion indices in each of the meal test |  | 8 months | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Chinese, Glucagon-like peptide 1, Glucagon, Insulin, Mixed meals, Healthy Adults