Modulating Glucose Tolerance With Dietary Tyrosine

Status Completed

Clinical Trial Summary

Metabolic or Bariatric surgery is an effective treatment for type 2 diabetes mellitus (T2DM) diabetes associated with obesity. There remain some questions about the biochemical mechanism that drive how these surgeries work to reverse hyperglycemia. In the proposed human studies, the investigators will test the hypothesis that the amino acid tyrosine is a key metabolite in regulating blood sugar levels and that manipulation of the amount tyrosine supplied by nutrition is able to achieve some of the metabolic benefits seen in the early post-surgical period following bariatric surgery. The central hypothesis is that that the tyrosine content of the meal challenge affects post-prandial intestinal and plasma dopamine and levodopa and L-3,4-dihydroxyphenylalanine (L-DOPA) levels, which, in turn, impact β-cell insulin secretion and glucose excursions. The investigators now propose to characterize the possible effects of manipulating dopamine and L-DOPA levels in the gut and plasma on glucose tolerance, insulin secretion, and insulin sensitivity in healthy volunteers with a range of body mass indexes (BMIs).

Clinical Trial Description

Several biochemical mechanisms explaining how Roux-en-Y Gastric Bypass (RYGB) provides an effective treatment for obesity associated type 2 diabetes mellitus (T2DM) and improves hyperglycemia independently of weight loss have been proposed. Two are of particular interest; a) the hindgut hypothesis suggesting that nutrient delivery to the distal intestine drives the production of "incretins" which enhance insulin secretion (e.g. glucagon-like peptide-1 (GLP-1)), and b) the foregut hypothesis, positing that foregut bypass reduces the secretion of factors (i.e. anti-incretins) that normally defend against hypoglycemia. The investigators have been actively investigating this topic and have developed a hypothesis based on past studies that they wish to test in a limited human clinical study. In addition, preclinical data suggest that there exists a gut-to-beta cell pathway, responsive to nutritional tyrosine, regulating insulin secretion, and this pathway provides a mechanism for the early postoperative improvements in hyperglycemia observed in RYGB. ;

Study Design

Related Conditions & MeSH terms

Glucose Tolerance

Clinical Trial Details

NCT number	NCT03872557
Study type	Interventional
Source	Columbia University
Contact
Status	Completed
Phase	N/A
Start date	August 7, 2019
Completion date	January 24, 2020

View Details

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Clinical trials are conducted in a series of steps, called phases - each phase is designed to answer a separate research question.

Phase 1: Researchers test a new drug or treatment in a small group of people for the first time to evaluate its safety, determine a safe dosage range, and identify side effects.
Phase 2: The drug or treatment is given to a larger group of people to see if it is effective and to further evaluate its safety.
Phase 3: The drug or treatment is given to large groups of people to confirm its effectiveness, monitor side effects, compare it to commonly used treatments, and collect information that will allow the drug or treatment to be used safely.
Phase 4: Studies are done after the drug or treatment has been marketed to gather information on the drug's effect in various populations and any side effects associated with long-term use.