Investigating the Use of Quercetin on Glucose Absorption in Obesity, and Obesity With Type 2 Diabetes
Condition: Obesity; Diabetes
MeSH terms: Obesity
Study type: Interventional
Phase: Phase 2

Summary: 
      Quercetin is a compound naturally found in various foods. It may have some role in the
      treatment of obesity and diabetes.

      The purpose of this study is to investigate research volunteers with obesity or obesity with
      type 2 diabetes to determine whether quercetin affects the way glucose is absorbed by the
      body.

      Thirty two participants aged 19 to 65 who are considered to be medically obese or obese with
      type 2 diabetes will be enrolled in this study. Before the onset of treatment, they will
      undergo a medical history, physical exam, blood work, and urinalysis. During the study,
      participants will be given an oral glucose tolerance test three times; during these tests
      they will receive 1 or 2 grams of quercetin, or placebo. Researchers will collect blood
      samples and analyze the effect of the treatment on blood glucose.
    

Detailed description: 
      Postprandial hyperglycemia and the resultant hyperinsulinemia contribute to the
      cardiovascular complications seen in obesity and in type 2 diabetes. Epidemiological studies
      suggest that slow absorption of carbohydrates dampens glucose and insulin peaks, and reduces
      cardiovascular morbidity. The polyphenol quercetin is the most abundant flavanoid in
      plant-derived foods, and is sold as a dietary supplement. In vitro, quercetin is a potent and
      reversible inhibitor of glucose transport by the intestinal glucose transporter GLUT2. In
      vivo quercetin inhibits post absorptive glucose peaks in obese, diabetic rats. We hypothesize
      that quercetin blunts intestinal glucose absorption in humans, and attenuates postprandial
      hyperglycemia. We propose to test, in a double blind placebo controlled study, whether
      coadministration of 1 or 2 grams of quercetin with glucose will reduce plasma glucose
      concentrations during a 6 hour oral glucose tolerance test with 3 to 6 grams of 3-O-methyl
      glucose (3OMG) in non-diabetic obese subjects and in obese type 2 diabetic subjects. The
      glucose dose may be varied from 0 to 100 grams to better understand the competition between
      3OMG and glucose. 3OMG is a non-metabolizable glucose analogue and is excreted unaltered in
      urine. 3OMG is not found in food and thus glucose absorption can be studies easily without
      the problem of a high baseline value. The use of 3OMG will provide a more accurate and true
      measures of glucose absorption. Study subjects will be 19 - 65 years with a body mass index
      greater than or equal to 30, without complications of diabetes, or on any medication other
      than oral hypoglycemic agents and aspirin. We will study 16 obese non diabetic subjects and
      16 obese type 2 diabetics. Each subject will have 3 oral glucose tolerance tests, and will
      serve as his or her own control. We will compare the peak plasma glucose concentrations
      achieved during oral glucose tolerance tests and the area under the curve of plasma glucose
      to determine whether quercetin inhibits glucose absorption in humans. Such inhibition may
      partially explain the protective effects of plant derived foods on cardiovascular disease,
      and enable us to use quercetin or related compounds to dampen intestinal glucose absorption.
      We will also measure quercetin concentrations in the plasma, in circulating white blood cells
      and in urine to determine quercetin pharmacokinetics. Additionally, to determine the optimal
      3OMG dose, we will study the absorption of glucose and 3OMG, without quercetin, in 12
      non-diabetic obese subjects and 12 lean subjects to serve as controls.
    

Intervention name(s): Quercetin; Placebo
Intervention type(s): Other; Other
Intervention description(s): 1 or 2 grams of quercetin or placebo will be given while patients undergo 6-hour OGTT
Intervention MeSH terms: Quercetin
Allocation: Non-Randomized
Intervention model: Crossover Assignment
Masking: Triple (Participant, Care Provider, Investigator)
Primary purpose: Basic Science
Keywords: Hyperglycemia; Hyperinsulinemia; OGTT; GLUT2; Post-Prandial; Type 2 Diabetes; Obesity