Effect of Whole Fruit on Glycemic Control in Adults With Type 2 Diabetes

March 1, 2024 updated by: Courtney M Peterson, University of Alabama at Birmingham

Diabetes costs the U.S. healthcare system more than any other disease, and nearly half of Americans will develop either diabetes or prediabetes in their lifetime. It is therefore critical to find new strategies to treat or reverse diabetes.

One such approach is adopting a healthy diet, which can dramatically improve blood sugar levels in adults with type 2 diabetes and even induce diabetes remission. Despite this, not much is known about which food groups are most effective at improving blood sugar levels in patients with diabetes.

Interestingly, of the various food groups that comprise the Mediterranean diet, epidemiologic data suggests that whole fruit may be one of the most efficacious at both preventing type 2 diabetes and improving blood sugar in patients with type 2 diabetes. However, few clinical trials have investigated the effects of whole fruit on blood sugar control. This study will therefore be the first to determine the effects of increasing whole fruit as a food group in type 2 diabetes patients. This supervised controlled feeding trial will test whether consuming a diet rich in whole fruit for 12 weeks can induce diabetes remission and can improve blood sugar, liver fat, and cardiovascular health in adults with type 2 diabetes. Thereafter, participants will be followed for up to one year. As a secondary aim, this study will also test whether consuming a large amount of fructose in whole food form negatively affects liver fat and cardiovascular health.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

Pre-registration notes: The primary endpoint is glycemic control, which will be analyzed hierarchically in descending order of importance as:

  1. Diabetes remission rate (endpoint #1)
  2. Medication effect score (endpoint #2)
  3. Fasting glucose and HbA1c (endpoints #3-4)
  4. Oral glucose tolerance test and continuous glucose monitoring measures (endpoints #5-14)

while the secondary endpoints (endpoints #15-20) will all be evaluated with equal importance.

Study Type

Interventional

Enrollment (Actual)

33

Phase

  • 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

  • Name: Cody J. Hanick, M.S.
  • Phone Number: 205-934-5458
  • Email: chanick@uab.edu

Study Contact Backup

  • Name: Courtney M. Peterson, Ph.D.
  • Phone Number: 205-934-0122
  • Email: cpeterso@uab.edu

Study Locations

  • United States
    • Alabama
      • Birmingham, Alabama, United States, 35233
        • Department of Nutrition Sciences, University of Alabamam at Birmingham

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

Ages Eligible for Study

20 years to 65 years (Adult, Older Adult)

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • 20-65 years old
  • BMI between 27.0-45.0 kg/m^2
  • First diagnosed with type 2 diabetes within the past 6 years
  • HbA1c between 6.0-9.5%%

Exclusion Criteria:

  • On insulin
  • Diagnosis of diabetes before age 18
  • Estimated glomerular filtration rate < 45 ml/min per 1.732 m^2
  • Heart attack in the past 6 months or severe or unstable heart failure
  • On weight loss medication
  • Change in the dosage of a chronic medication that may affect study endpoints within the past 3 months
  • Clinically significant laboratory abnormality (e.g. abnormal hemoglobin levels)
  • Significant gastrointestinal disease, major gastrointestinal surgery, or gallstones
  • Significant cardiovascular, renal, cardiac, liver, lung, adrenal, or nervous system disease that might compromise safety or data validity
  • Evidence of cancer (other than non-melanoma skin cancer) within the last 5 years
  • Lost or gained more than 5 kg of weight in the past 6 months
  • Pregnant, planning to become pregnant in the next 12 months, or breastfeeding
  • Major psychiatric condition that would affect the ability to participate in the study
  • Not able to eat the provided study meals
  • Behavioral factors or circumstances that may impede adhering to the dietary intervention
  • Not able to do the MRI/MRS abdominal scan, such as due to claustrophobia, implanted metal objects, or a body girth of 60 cm or greater

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: N/A
  • Interventional Model: Single Group Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: High-Fruit Diet
Whole fruit-rich diet (~50% of calories from whole fruit)
Behavioral: High-Fruit Diet
Participants will consume a diet rich in whole fruit. During Phase I (Weeks 1-4; supervised controlled feeding), participants will gradually increase the amount of whole fruit they consume, eventually reaching 50% of calories from whole fruit. In Phase II (Week 5-12; supervised controlled feeding), participants will consume a whole fruit-rich, eucaloric diet that provides 50% of calories in the form of whole fruit. The non-fruit portion of the diet will be styled as a Mediterranean Diet. Participants will be required to approximately keep their weight stable during Phases I and II. In the Follow-Up Phase (Months 4-12; free-living), participants will be instructed to continue consuming at least one-third of their diet as whole fruit and to make healthy food choices.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Diabetes remission rate
Time Frame: Change from baseline (Week 0) to Weeks 4 and 12 and follow-up Months 6, 9, and 12
Remission rate will be measured in two ways. At the end of Phase II, it will be quantified as the percentage of patients who achieve non-diabetic levels of fasting glucose without the aid of any anti-hyperglycemic pharmacologic therapy or ongoing procedures.. During the Follow-up period, it will be quantified as the percentage of patients who achieve non-diabetic levels of both fasting glucose and HbA1c without the aid of any anti-hyperglycemic pharmacologic therapy or ongoing procedures.
Change from baseline (Week 0) to Weeks 4 and 12 and follow-up Months 6, 9, and 12
Diabetes medication usage
Time Frame: Change from baseline to Weeks 4 and 12 and follow-up Months 6, 9, and 12
As quantified by the Medication Effect Score
Change from baseline to Weeks 4 and 12 and follow-up Months 6, 9, and 12
Fasting glucose
Time Frame: Change from baseline to Weeks 4 and 12 and follow-up Months 6, 9, and 12
mg/dl
Change from baseline to Weeks 4 and 12 and follow-up Months 6, 9, and 12
HbA1c
Time Frame: Change from baseline to Weeks 4 and 12 and follow-up Months 6, 9, and 12
percentage
Change from baseline to Weeks 4 and 12 and follow-up Months 6, 9, and 12
2-hour glucose tolerance
Time Frame: Change from baseline to Weeks 4 and 12
mg/dl
Change from baseline to Weeks 4 and 12
Mean glucose during a 3-hour Oral Glucose Tolerance Test (OGTT)
Time Frame: Change from baseline to Weeks 4 and 12
mg/dl
Change from baseline to Weeks 4 and 12
Mean insulin during a 3-hour OGTT
Time Frame: Change from baseline to Weeks 4 and 12
mU/l
Change from baseline to Weeks 4 and 12
Mean C-peptide during a 3-hour OGTT
Time Frame: Change from baseline to Weeks 4 and 12
ng/ml
Change from baseline to Weeks 4 and 12
Fasting insulin
Time Frame: Change from baseline to Weeks 4 and 12 and follow-up Months 6, 9, and 12
mU/l
Change from baseline to Weeks 4 and 12 and follow-up Months 6, 9, and 12
Fasting C-peptide
Time Frame: Change from baseline to Weeks 4 and 12 and follow-up Months 6, 9, and 12
ng/ml
Change from baseline to Weeks 4 and 12 and follow-up Months 6, 9, and 12
Insulin sensitivity
Time Frame: Change from baseline to Weeks 4 and 12
Insulin sensitivity (dl/kg/min/μU/ml) during a 3-hour OGTT, as measured by the Oral Minimal Model
Change from baseline to Weeks 4 and 12
Insulin secretion
Time Frame: Change from baseline to Weeks 4 and 12
Beta-cell responsivity index during a 3-hour OGTT, as measured by the Oral Minimal Model
Change from baseline to Weeks 4 and 12
Beta-cell function
Time Frame: Change from baseline to Weeks 4 and 12
Insulinogenic index as measured during the first 15 minutes of a 3-hour OGTT
Change from baseline to Weeks 4 and 12
Mean 24-hour glucose levels, peak glucose levels, and mean amplitude of glycemic excursions (MAGE), as measured using continuous glucose monitoring
Time Frame: Change from baseline to Weeks 4 and 12
mg/dl
Change from baseline to Weeks 4 and 12

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Intrahepatic lipid (liver fat)
Time Frame: Change from baseline to Weeks 4 and 12
Percentage as measured using Magnetic Resonance Spectroscopy (MRS) and 3-point M-Dixon Magnetic Resonance Imaging (MRI)
Change from baseline to Weeks 4 and 12
Fasting lipids
Time Frame: Change from baseline to Weeks 4 and 12 and follow-up Months 6, 9, and 12
Total cholesterol (mg/dl), LDL cholesterol (mg/dl), HDL cholesterol (mg/dl), and triglycerides (mg/dl)
Change from baseline to Weeks 4 and 12 and follow-up Months 6, 9, and 12
Systolic and diastolic blood pressure
Time Frame: Change from baseline to Weeks 4 and 12 and follow-up Months 6, 9, and 12
mm Hg
Change from baseline to Weeks 4 and 12 and follow-up Months 6, 9, and 12
Heart rate
Time Frame: Change from baseline to Weeks 4 and 12 and follow-up Months 6, 9, and 12
beats per minute
Change from baseline to Weeks 4 and 12 and follow-up Months 6, 9, and 12
Number of cardiovascular medications used
Time Frame: Change from baseline to Weeks 4 and 12 and follow-up Months 6, 9, and 12
Number for each category of medication (e.g., anti-hypertensive medications)
Change from baseline to Weeks 4 and 12 and follow-up Months 6, 9, and 12
Dosage of cardiovascular medications used
Time Frame: Change from baseline to Weeks 4 and 12 and follow-up Months 6, 9, and 12
Dosages for each category of medication (e.g., anti-hypertensive medications)
Change from baseline to Weeks 4 and 12 and follow-up Months 6, 9, and 12

Other Outcome Measures

Outcome Measure
Measure Description
Time Frame
Body weight
Time Frame: Change from baseline to Weeks 4 and 12 and follow-up Months 6, 9, and 12
kg
Change from baseline to Weeks 4 and 12 and follow-up Months 6, 9, and 12
Waist circumference
Time Frame: Change from baseline to Weeks 4 and 12 and follow-up Months 6, 9, and 12
cm
Change from baseline to Weeks 4 and 12 and follow-up Months 6, 9, and 12
Pancreatic fat
Time Frame: Change from baseline to Weeks 4 and 12
Percentage as measured using MRS and 3-point M-Dixon MRI methods
Change from baseline to Weeks 4 and 12
Visceral fat
Time Frame: Change from baseline to Weeks 4 and 12
kg as measured using MRI
Change from baseline to Weeks 4 and 12
Subcutaneous abdominal fat
Time Frame: Change from baseline to Weeks 4 and 12
kg as measured using MRI
Change from baseline to Weeks 4 and 12
Gut microbiome diversity
Time Frame: Change from baseline to Weeks 4 and 12
Diversity metrics (i.e., alpha and beta diversity)
Change from baseline to Weeks 4 and 12
Gut microbiome composition
Time Frame: Change from baseline to Weeks 4 and 12
Taxonomic composition and abundances
Change from baseline to Weeks 4 and 12
Transcriptome
Time Frame: Change from baseline to Weeks 4 and 12
Fold change in gene expression within blood cells (includes pathway analyses)
Change from baseline to Weeks 4 and 12
Preference and sensitivity to sweet tastes
Time Frame: Change from baseline to Weeks 4 and 12
As measured on a 0-100 mm visual analog scale (VAS), using a Sweetness Taste Test
Change from baseline to Weeks 4 and 12
Caloric intake
Time Frame: Change from baseline to Week 4 and follow-up Month 12
kcal/day as measured using 7-day food records
Change from baseline to Week 4 and follow-up Month 12
Macronutrient composition
Time Frame: Change from baseline to Week 4 and follow-up Month 12
Percentage of calories as measured using 7-day food records
Change from baseline to Week 4 and follow-up Month 12
Diet satisfaction
Time Frame: Change from baseline to Weeks 4 and 12
As measured on a 0-100 mm visual analog scale (VAS)
Change from baseline to Weeks 4 and 12
Food intake
Time Frame: Change from baseline to Week 4 and follow-up Month 12
Percent intake of individual food categories as measured using 7-day food records
Change from baseline to Week 4 and follow-up Month 12
Habitual fruit consumption
Time Frame: Change from baseline to Weeks 4 and 12 and follow-up Months 6, 9, and 12
As estimated using a series of semi-quantitative food frequency questions from the Diet History Questionnaire
Change from baseline to Weeks 4 and 12 and follow-up Months 6, 9, and 12
Food cravings
Time Frame: Change from baseline to Weeks 4 and 12
As measured on five-point scales by the Food Craving Inventory-II
Change from baseline to Weeks 4 and 12
Fruit type preferences
Time Frame: Change from baseline to Weeks 4 and 12
As measured by VAS on a 0-100 mm scale
Change from baseline to Weeks 4 and 12
Food attitudes and behaviors
Time Frame: Change from baseline to Weeks 4 and 12
As measured by a modified version of the National Cancer Institute (NCI) 2007 Food Attitudes and Behaviors Survey, which covers constructs including attitudes and beliefs, fruit and vegetable consumption, eating behaviors, and food preferences
Change from baseline to Weeks 4 and 12
General health status
Time Frame: Change from baseline to Weeks 4 and 12
Healthy days (along various dimensions) as measured by the Centers for Disease Control and Prevention's (CDC) Health-Related Qualify of Life questionnaire
Change from baseline to Weeks 4 and 12
Depression
Time Frame: Change from baseline to Weeks 4 and 12
As measured on a 0-27 point scale by the Patient Health Questionnaire-9
Change from baseline to Weeks 4 and 12
Mood states
Time Frame: Change from baseline to Weeks 4 and 12
As measured on a 5-point scale by the Profile of Mood States Short-Form
Change from baseline to Weeks 4 and 12
Intervention satisfaction and feedback
Time Frame: Week 12
As measured by qualitative exit interview
Week 12

Collaborators and Investigators

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

Sponsor

University of Alabama at Birmingham

Investigators

  • Principal Investigator: Courtney M. Peterson, Ph.D., University of Alabama at Birmingham

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 (Actual)

September 10, 2019

Primary Completion (Actual)

September 5, 2023

Study Completion (Actual)

February 5, 2024

Study Registration Dates

First Submitted

November 16, 2018

First Submitted That Met QC Criteria

November 28, 2018

First Posted (Actual)

November 29, 2018

Study Record Updates

Last Update Posted (Actual)

March 5, 2024

Last Update Submitted That Met QC Criteria

March 1, 2024

Last Verified

March 1, 2024

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • IRB-300001719

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

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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