Effects of Whole Fruit on Blood Sugar in People With Type 2 Diabetes

NCT07376226 | Not Yet Recruiting

• 1 other identifier: 25-1444
• Study Type: interventional
• Target: 25
• Locations: 1 country
• Sites: 1

Brief Summary

This study will determine the effects of consuming whole fruit on blood sugar control, liver fat, and cardiovascular health in adults with type 2 diabetes who are not treated with insulin.

Conditions

Type 2 Diabetes

Keywords

type 2 diabetes; whole fruit; dietary intervention; glycemic control; liver fat; continuous glucose monitoring; blood sugar; nutrition; fruit; glucose; insulin; blood pressure; carbohydrates; high-carbohydrate diet

Outcome Measures

Primary Outcomes (9)

• Mean 24-hour Glucose Levels

  Average 24-hour interstitial glucose levels (mg/dl), as measured by continuous glucose monitoring (CGM). If needed, data will be adjusted for any changes in antihyperglycemic medication use, using the medication effect score (MES).

  Change from baseline to week 17

• Mean 3-hour Glucose Levels

  Mean glucose (mg/dl) during a 3-hour oral glucose tolerance test (OGTT)

  Change from baseline to week 17

• Mean 3-hour Insulin

  Mean insulin (mU/l) during a 3-hour OGTT

  Change from baseline to week 17

• Mean 3-hour C-Peptide

  Mean C-Peptide (ng/ml) during a 3-hour OGTT

  Change from baseline to week 17

• Insulin Sensitivity

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

  Change from baseline to week 17

• Dynamic Beta-Cell Responsivity

  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

  Change from baseline to week 17

• Static Beta-Cell Responsivity

  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.

  Change from baseline to week 17

• Glycemic Variability

  Measures of glucose variability derived from continuous glucose monitoring, including mean amplitude of glycemic excursions and standard deviation (mg/dl).

  Change from baseline to week 17

• Time-in-range Metrics from CGM

  Standard time-in-range metrics, including time-below-range (TBR), time-in-range (TIR), and time-above-range (TAR), as standardized by the International Consensus on Time in Range. Values will be reported as percentages of the 24-hour day.

  Change from baseline to week 17

Secondary Outcomes (5)

• Intrahepatic Lipid (Liver Fat)

  Change from baseline to week 17

• Body Weight

  Change from baseline to week 17

• Systolic and Diastolic Blood Pressure

  Change from baseline to week 17

• Heart Rate

  Change from baseline to week 17

• Lipids

  Change from baseline to week 17

Study Arms (1)

Whole Fruit

EXPERIMENTAL

Participants will consume a large amount of whole fruit, constituting 50% of total calories.

Other: Whole Fruit

Interventions

Whole Fruit OTHER

Participants will consume a large amount of whole fruit for 17 weeks. During the first 6.5 weeks, participants will gradually increase the amount of whole fruit they eat by 5% every 5 days. Once they reach 50% of their calories as whole fruit, they will continue to eat 50% fruit for the remaining 10.5 weeks of the study. This is a controlled feeding study, so participants will consume fruit prepared in a metabolic kitchen. The fruit will consist of fresh fruit, dried fruit, and frozen fruit blended into smoothies. To demonstrate compliance, participants will video-record themselves eating the provided fruit. All participants will receive the same dietary intervention. Participants will otherwise continue their usual diet and lifestyle habits.

Whole Fruit

Eligibility Criteria

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

You may qualify if:

• Aged ≥18 years
• Diagnosed with type 2 diabetes
• HbA1c between 6.5-12.0%
• Fasting C-peptide level ≥0.5 ng/ml, indicating the patient does not have beta-cell failure, as measured at screening

You may not qualify if:

• On insulin
• Evidence of latent autoimmune diabetes (LADA) or maturity-onset diabetes of the young (MODY)
• Estimated glomerular filtration rate (eGFR) \<45 ml/min per 1.73 m²
• Heart attack in the past 6 months or severe/unstable heart failure
• On weight loss medication, including GLP-1 receptor agonists (e.g., semaglutide, dulaglutide)
• 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 participant safety or data validity
• Evidence of cancer (other than non-melanoma skin cancer) within the last 5 years
• Lost or gained more than 5 lbs (or more than 2% of body weight if the patient weighs \>250 lbs) of weight in the past 2 months
• Pregnant, planning to become pregnant in the next 6 months, or breastfeeding
• Major psychiatric condition that would affect the ability to participate in the study
• Not able to eat the provided study meals (e.g., food allergies)
• Behavioral factors or circumstances that may impede adherence to the dietary intervention

Sponsors & Collaborators

• Harvard School of Public Health (HSPH): lead

Study Sites (1)

Harvard T. H. Chan School of Public Health

Boston, Massachusetts, 02115, United States

Location

Related Publications (1)

• 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

MeSH Terms

Conditions

Diabetes Mellitus, Type 2; Fatty Liver; Insulin Resistance

Condition Hierarchy (Ancestors)

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

Study Officials

• Courtney M Peterson

  Harvard School of Public Health (HSPH)

  PRINCIPAL INVESTIGATOR

Central Study Contacts

Kathleen Johnson Research Project Manager, MPH, RD

CONTACT

617-998-6333; fruit2@hsph.harvard.edu

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: NA
• Masking: NONE
• Masking Details: Nurses and technicians who perform the assays and assessments will be blinded and will not be affiliated with the study. Data will be cleaned blinded by randomizing the order of the timepoints.
• Purpose: TREATMENT
• Intervention Model: SINGLE GROUP
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Associate Professor, Department of Nutrition

Study Record Dates

• First Submitted: January 22, 2026
• First Posted: January 29, 2026
• Study Start: April 1, 2026
• Primary Completion (Estimated): October 1, 2027
• Study Completion (Estimated): April 1, 2028
• Last Updated: February 3, 2026

Record last verified: 2026-01

Data Sharing

• IPD Sharing: Will not share

Locations

US (1)