Metabolic Benefits of Drinking Blueberry Tea in Type 2 Diabetes

April 4, 2021 updated by: Michelle Keske, Menzies Institute for Medical Research
Plant derived compounds, e.g. flavonoids from dark chocolate, green tea, or blueberries, show great potential as nutraceuticals for the treatment of various diseases such as type 2 diabetes (T2D). Flavonoids have been suggested to improve glucose metabolism, reduce blood lipids, reduce oxidative stress and improve vascular function. For these reasons we recently investigated the effects of daily consumption of locally produced blueberry tea and demonstrated that this could partially restore insulin sensitivity in an animal model. We propose to translate these findings to assess the efficacy of this nutraceutical as a new treatment for improving glucose tolerance in people with T2D.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

Current treatments for T2D are limited, have unwanted side effects, and lose effectiveness over time. There is a growing public interest in the use of complementary and alternative approaches for treating insulin resistance and T2D. Blueberries, blueberry leaves and cinnamon have each been reported to improve insulin sensitivity or insulin action. Blueberry Boost™ is a locally produced Blueberry Tea and is a proprietary blend of dried blueberries (37% wt/wt), blueberry leaves, raspberry leaves, spearmint leaves and cinnamon.

It is well established that improving glycemic control is important for managing insulin resistance and T2D and the associated vascular pathologies that directly contribute to end-organ damage (microvascular disease), hypertension and cardiovascular disease (stroke, heart attack and heart failure). We have recently demonstrated that a unique blueberry tea blend fully restores the vascular insulin sensitivity in muscle of the high-fat fed insulin-resistant rat model and is associated with substantial improvements in muscle glucose uptake and whole body insulin sensitivity. We propose to translate these findings to assess the efficacy of this nutraceutical as a new treatment for improving glucose tolerance in people with T2D.

Aim: Determine whether chronic consumption (4 weeks) of blueberry tea can improve metabolic and vascular health in people with and without T2D.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Anticipated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
36

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Locations

  • Australia
    • Tasmania
      • Hobart, Tasmania, Australia, 7000
        • Recruiting
        • Menzies Institute for Medical Research
        • Contact:
        • Contact:
          • Keske

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

18 years to 75 years (Adult, Older Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Description

Inclusion Criteria:

  • Aged 18-75 years.
  • Normal to overweight (BMI 19-35 kg/m2).
  • On lifestyle or metformin only diabetes treatment.
  • Normotensive (seated brachial blood pressure <160/100 mmHg).
  • No history of T2D (e.g. fasting plasma glucose <7.0mM); or with clinically diagnosed T2D on metformin or lifestyle intervention only (e.g. fasting plasma glucose ≥7.0mM, HbA1c).
  • Willing to drink blueberry tea for 4 weeks (3 times per day with meals).

Exclusion Criteria:

  • Age <18 yrs or >76 yrs
  • Morbidly obese with a BMI ≥36 kg/m2
  • Not on lifestyle and/or metformin only treatment for diabetes (e.g. insulin injections, sulphonylureas).
  • History of myocardial infarction or stroke
  • History of malignancy within past 5 years (except for non-melanoma skin cancers)
  • Current smoker
  • History of severe liver disease
  • History of drug or alcohol abuse
  • Elective major surgery during the course of the study
  • Pregnancy/lactation
  • Currently consuming (or have regularly consumed in the past 2 months) blueberry tea, or supplements containing blueberries, blueberry leaves, raspberry leaves, spearmint or cinnamon.
  • Participation or intention to participate in another clinical research study during the study period.
  • Not willing to consume blueberry tea for 4 weeks.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Crossover Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: Blueberry Tea
3 cups of blueberry tea per day x 4 weeks
Other: Blueberry Tea
Blueberry Tea
No Intervention: No Treatment

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Improvement in Glucose Tolerance after 4 weeks of drinking blueberry tea.
Time Frame: 4 weeks
Oral glucose tolerance test (75g glucose) measured on 3 occasions: at baseline, after 4 weeks of drinking blueberry tea, and after 4 weeks of no treatment (randomized cross-over design). Blood glucose and plasma insulin levels measured at 0, 15, 30, 60, 90 and 120 min following consumption of glucose load.
4 weeks

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Improvement in Hemoglobin A1c (HbA1c) levels after 4 weeks of drinking blueberry tea.
Time Frame: 4 weeks.
HbA1c levels measured on 3 occasions: at baseline, after 4 weeks of drinking blueberry tea, and after 4 weeks of no treatment (randomized cross-over design).
4 weeks.
Improvement in fasting Serum Lipid (cholesterol, HDL, LDL,triglycerides) levels after 4 weeks of drinking blueberry tea.
Time Frame: 4 weeks
Fasting serum lipids (cholesterol, HDL, LDL,triglycerides) measured on 3 occasions: at baseline, after 4 weeks of drinking blueberry tea, and after 4 weeks of no treatment (randomized cross-over design).
4 weeks
Improvement in fasting serum pro-inflammatory cytokine (IL-6, IL-1b, CRP, TNFa) levels after 4 weeks of drinking blueberry tea.
Time Frame: 4 weeks
Fasting serum pro-inflammatory cytokines (IL-6, IL-1b, CRP, TNFa) assessed by ELISA will be measured on 3 occasions: at baseline, after 4 weeks of drinking blueberry tea, and after 4 weeks of no treatment (randomized cross-over design).
4 weeks
Improvement in fasting serum albumin levels after 4 weeks of drinking blueberry tea..
Time Frame: 4 weeks
Fasting serum albumin levels measured on 3 occasions: at baseline, after 4 weeks of drinking blueberry tea, and after 4 weeks of no treatment (randomized cross-over design).
4 weeks
Fasting serum electrolytes (Na, K, Cl, HCO3).
Time Frame: 4 weeks
Fasting serum electrolytes (Na, K, Cl, HCO3) measured on 3 occasions: at baseline, after 4 weeks of drinking blueberry tea, and after 4 weeks of no treatment (randomized cross-over design).
4 weeks
Improvement in Resting Blood Pressure (central and brachial blood pressure) after 4 weeks of drinking blueberry tea.
Time Frame: 4 weeks
Blood Pressure (central and brachial blood pressure) will be measured by Mobil-O-Graph and assessed on 3 occasions: at baseline, after 4 weeks of drinking blueberry tea, and after 4 weeks of no treatment (randomized cross-over design).
4 weeks
Improvement in resting Augmentation Index after 4 weeks of drinking blueberry tea.
Time Frame: 4 weeks
Augmentation index will be measured by Mobil-O-Graph and assessed on 3 occasions: at baseline, after 4 weeks of drinking blueberry tea, and after 4 weeks of no treatment (randomized cross-over design).
4 weeks
Improvement in large artery stiffness after 4 weeks of drinking blueberry tea.
Time Frame: 4 weeks
Large artery stiffness will be measured by Mobil-O-Graph and assessed on 3 occasions: at baseline, after 4 weeks of drinking blueberry tea, and after 4 weeks of no treatment (randomized cross-over design).
4 weeks

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Menzies Institute for Medical Research

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Michelle A Keske, PhD, Menzies Institute for Medical Research

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
November 1, 2015

Primary Completion (Anticipated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
December 1, 2021

Study Completion (Anticipated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
December 1, 2021

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
December 3, 2015

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
December 10, 2015

First Posted (Estimate)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
December 15, 2015

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
April 6, 2021

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
April 4, 2021

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
April 1, 2021

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • H0014873

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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