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

NCT03758742 | Completed Results

• 2 other identifiers: IRB-300001719P30DK079626
• Study Type: interventional
• Target: 34
• Locations: 1 country
• Sites: 1

Brief Summary

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, 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 improve glycemic control and cardiometabolic health in weight-stable adults with type 2 diabetes. The primary endpoint is glycemic control. Since changes in medication doses can skew the interpretation of glycemic outcomes, glycemic control will be assessed hierarchically (in descending order of importance) using (a) attainment of nondiabetic glycemia without medications (as a proxy for diabetes remission), (b) medication effect scores, (c) mean glucose during an oral glucose tolerance test, and (d) 24-hour mean glucose from continuous glucose monitoring. As secondary aims, this study will also test whether consuming a large amount of fructose in whole food form affects liver fat, pancreatic fat, and cardiovascular disease risk factors.

Conditions

Diabetes Mellitus, Type 2

Keywords

type 2 diabetes; whole fruit; diabetes remission; glycemic control; liver fat; intrahepatic lipid; controlled feeding trial

Outcome Measures

Primary Outcomes (4)

• Diabetes Remission Rate

  Percentage of patients who can maintain non-diabetic levels 24-hour mean glucose without the aid of pharmacotherapy at week 12

  Change from baseline to week 12

• Medication Effect Score (MES)

  % (or percentage). This quantity estimates the percentage by which all anithyperglycemic medications taken by a patient would lower HbA1c levels (i.e., percent of glycated hemoglobin molecules). Higher values indicate a higher dose and/or potency of medications.

  Change from baseline to Week 12

• Mean Glucose During a 3-hour Oral Glucose Tolerance Test (OGTT)

  mg/dl

  Changes from weeks 0 to 12 (primary timepoint) and weeks 0 to 4 and 4 to 12 (secondary timepoints). Change from week 0 to 12 reported.

• Mean 24-hour Glucose Levels as Measured by Continuous Glucose Monitoring (CGM), Adjusted for Any Changes in Medication Doses Via the MES

  mg/dl

  Changes from weeks 0 to 12 (primary timepoint) and weeks 0 to 4 and 4 to 12 (secondary timepoints). Change from week 0 to 12 reported.

Secondary Outcomes (14)

• Insulin Sensitivity

  Changes from weeks 0 to 12 (primary timepoint) and weeks 0 to 4 and 4 to 12 (secondary timepoints). Change from week 0 to 12 reported.

• Dynamic Beta-Cell Responsivity

  Changes from weeks 0 to 12 (primary timepoint) and weeks 0 to 4 and 4 to 12 (secondary timepoints). Change from week 0 to 12 reported.

• Static Beta-Cell Responsivity

  Changes from weeks 0 to 12 (primary timepoint) and weeks 0 to 4 and 4 to 12 (secondary timepoints). Change from week 0 to 12 reported.

• Mean Insulin During a 3-hour OGTT

  Changes from weeks 0 to 12 (primary timepoint) and weeks 0 to 4 and 4 to 12 (secondary timepoints). Change from week 0 to 12 reported.

• Mean C-peptide During a 3-hour OGTT

  Changes from weeks 0 to 12 (primary timepoint) and weeks 0 to 4 and 4 to 12 (secondary timepoints). Change from week 0 to 12 reported.

Other Outcomes (16)

• Body Weight

  Changes from weeks 0 to 12 (primary timepoint) and weeks 0 to 4 and 4 to 12 (secondary timepoints); assessed weekly

• Waist Circumference

  Changes from weeks 0 to 12 (primary timepoint) and weeks 0 to 4 and 4 to 12 (secondary timepoints)

• Visceral Fat

  Changes from weeks 0 to 12 (primary timepoint) and weeks 0 to 4 and 4 to 12 (secondary timepoints)

Study Arms (1)

High-Fruit Diet

EXPERIMENTAL

Whole fruit-rich diet (\~50% of calories from whole fruit)

Behavioral: High-Fruit Diet

Interventions

High-Fruit Diet BEHAVIORAL

In this supervised controlled feeding study, participants will consume a diet rich in whole fruit. During the Ramp-Up Phase (Weeks 1-4), participants will gradually increase the amount of whole fruit they consume, eventually reaching 50% of calories from whole fruit. In the Main Phase (Weeks 5-12), 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 throughout the intervention.

High-Fruit Diet

Eligibility Criteria

• Age: 20 Years - 70 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

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

You may not qualify if:

• 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

Sponsors & Collaborators

• University of Alabama at Birmingham: lead
• National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK): collaborator

Study Sites (1)

Department of Nutrition Sciences, University of Alabamam at Birmingham

Birmingham, Alabama, 35233, United States

Location

Related Publications (2)

• Cobelli C, Dalla Man C, Toffolo G, Basu R, Vella A, Rizza R. The oral minimal model method. Diabetes. 2014 Apr;63(4):1203-13. doi: 10.2337/db13-1198.

  PMID: 24651807 BACKGROUND

• Hanick CJ, Berg KJ, Garvey WT, Goss AM, Steger FL, Richman JS, Peterson CM. Study protocol, menu design, and rationale for a study testing the effects of a whole fruit-rich diet on glycemic control, liver fat, pancreatic fat, and cardiovascular health in adults with type 2 diabetes. Nutr Res. 2025 Mar;135:82-100. doi: 10.1016/j.nutres.2025.01.008. Epub 2025 Jan 27.

  PMID: 39978247 DERIVED

MeSH Terms

Conditions

Diabetes Mellitus, Type 2; Fatty Liver

Condition Hierarchy (Ancestors)

Diabetes Mellitus; Glucose Metabolism Disorders; Metabolic Diseases; Nutritional and Metabolic Diseases; Endocrine System Diseases; Liver Diseases; Digestive System Diseases

Results Point of Contact

• Title: Dr. Courtney M. Peterson
• Organization: University of Alabama at Birmingham

cpeterso@uab.edu

205-934-0122

Study Officials

• Courtney M. Peterson, Ph.D.

  University of Alabama at Birmingham

  PRINCIPAL INVESTIGATOR

Publication Agreements

• PI is Sponsor Employee: No
• Restrictive Agreement: No

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: NA
• Masking: NONE
• Masking Details: Lab values and week 0, 4, and 12 endpoints are assessed blinded by individuals not affiliated with the protocol. Also, data cleaning will be performed while being blinded to the timepoint.
• Purpose: TREATMENT
• Intervention Model: SINGLE GROUP
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Associate Professor

Study Record Dates

• First Submitted: November 16, 2018
• First Posted: November 29, 2018
• Study Start: September 10, 2019
• Primary Completion: September 5, 2023
• Study Completion: September 5, 2023
• Last Updated: June 10, 2025
• Results First Posted: May 23, 2025

Record last verified: 2025-05

Locations

US (1)