Skip to main content
OpenTrials
Completed

NCT Number: NCT03758742

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

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.

Completed

Looking for future studies?

Notify Me

Key information

Conditions

Diabetes Mellitus, Type 2 Diabetes Mellitus Digestive System Diseases Endocrine System Diseases Fatty Liver Glucose Metabolism Disorders Liver Diseases Metabolic Diseases Nutritional and Metabolic Diseases

Age range

20 year–70 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Department of Nutrition Sciences, University of Alabamam at Birmingham

Birmingham, Alabama, 35233, United States

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • 20-70 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%%

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

Treatment and study plan

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.

Primary outcomes

  1. Diabetes Remission Rate

    Time frame: Change from baseline to week 12

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

  2. Medication Effect Score (MES)

    Time frame: Change from baseline to Week 12

    % (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.

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

    Time frame: 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.

    mg/dl

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

    Time frame: 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.

    mg/dl

Secondary outcomes

  1. Insulin Sensitivity

    Time frame: 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.

    Insulin sensitivity (dl/kg/min/μU/ml) during a 3-hour OGTT, as measured by the Oral C-Peptide Minimal Model.

  2. Dynamic Beta-Cell Responsivity

    Time frame: 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.

    Phi_dynamic during a 3-hour OGTT, as measured by the Oral C-Peptide Minimal Model (which is a set of 5 coupled differential equations; see reference under Citations). Phi_dynamic is a measure of beta-cell responsiveness during first-phase insulin secretion. It is a dimensionless index (arbitrary units), where higher values denote greater insulin secretion.

  3. Static Beta-Cell Responsivity

    Time frame: 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.

    Phi_static during a 3-hour OGTT, as measured by the Oral C-Peptide Minimal Model (which is a set of 5 coupled differential equations; see reference under Citations). Phi_static is a measure of beta-cell responsiveness during second-phase insulin secretion. The units of measure are min^-1, and higher values denote greater insulin secretion.

  4. Mean Insulin During a 3-hour OGTT

    Time frame: 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.

    mU/l

  5. Mean C-peptide During a 3-hour OGTT

    Time frame: 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.

    ng/ml

  6. Mean Amplitude of Glycemic Excursions From CGM

    Time frame: Changes from weeks 0 to 12 (primary timepoint) and weeks 0 to 4 and 4 to 12 (secondary timepoints)"

    mg/dl

  7. Fasting Glucose

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

    mg/dl

  8. HbA1c

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

    percentage

  9. Liver Fat (Intrahepatic Lipid)

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

    Percentage as measured using Magnetic Resonance Spectroscopy (MRS) and 3-point M-Dixon Magnetic Resonance Imaging (MRI)

  10. Pancreatic Fat

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

    Percentage as measured using MRS and 3-point M-Dixon MRI methods

  11. Systolic and Diastolic Blood Pressure

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

    mm Hg

  12. Heart Rate

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

    beats per minute

  13. Time-in-range Metrics From CGM

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

    Time during which glucose levels are between 70 and 300 mg/dl

  14. Lipids

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

    Fasting total cholesterol (mg/dl), LDL cholesterol (mg/dl), HDL cholesterol (mg/dl), and triglycerides (mg/dl)

Other outcomes

  1. Body Weight

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

    kg

  2. Waist Circumference

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

    cm

  3. Visceral Fat

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

    Visceral fat as measured using MRI (kg)

  4. Subcutaneous Abdominal Fat

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

    Subcutaneous abdominal fat as measured using MRI (kg)

  5. Gut Microbiome Diversity

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

    Diversity metrics (i.e., alpha and beta diversity)

  6. Gut Microbiome Composition

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

    Taxonomic composition and abundances

  7. Preference and Sensitivity to Sweet Tastes

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

    As measured on a 0-100 mm visual analog scale (VAS), using a Sweetness Taste Test

  8. Diet Satisfaction

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

    As measured on a 0-100 mm visual analog scale (VAS)

  9. 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

  10. Food Cravings

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

    As measured on five-point scales by the Food Craving Inventory-II

  11. Fruit Liking Visual Analog Scales

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

    As measured by VAS on a 0-100 mm scale

  12. Food Attitudes and Behaviors

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

    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

  13. General Health Status

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

    Healthy days (along various dimensions) as measured by the Centers for Disease Control and Prevention's (CDC) Health-Related Qualify of Life questionnaire

  14. Depression

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

    As measured on a 0-27 point scale by the Patient Health Questionnaire-9

  15. Mood States

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

    As measured on a 5-point scale by the Profile of Mood States Short-Form

  16. Intervention Satisfaction and Feedback

    Time frame: Week 12

    As measured by qualitative exit interview

Sponsors and collaborators

Lead sponsor

University of Alabama at Birmingham

Other

Collaborators

  • National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)

Registry information

Important dates

Study start
2019
Primary completion
2023
Study completion
2023
First posted
Nov 29, 2018
Registry last updated
Jun 10, 2025

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

Related clinical trials

Published trials that share one or more normalized conditions with this study.