An interventional study of Whole Fruit in Type 2 Diabetes, sponsored by Harvard School of Public Health (HSPH). Not yet recruiting at 1 site in United States. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-07-07.
Sponsored by Harvard School of Public Health (HSPH) · Not applicable, Interventional, and Treatment
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.
Diabetes is one of the top three drivers of healthcare costs in the U.S., 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 in some patients. Despite this, not much is known about which food groups are most effective at improving blood sugar levels in patients with diabetes.
Although individuals with type 2 diabetes are often advised to reduce carbohydrate intake, current dietary guidelines also recommend consuming fruit and other carbohydrate-rich foods. This has led to confusion among patients and clinicians about whether eating fruit, particularly in larger amounts, is beneficial or harmful for blood sugar and overall health. Whole fruit differs from many other carbohydrate sources in that whole fruit is rich in fiber, vitamins, minerals, and bioactive plant compounds, while being relatively low in energy density.
Most prior research examining the effects of whole fruit in people with type 2 diabetes has been epidemiologic, focused on individual fruits, or combined whole fruit with fruit juice and/or vegetables into a single food category. As a result, it is unknown how whole fruit, as a food category, affects glycemic control and cardiovascular health.
The investigators previously found that a whole-fruit-rich, Mediterranean-style diet improved blood sugar control and blood pressure in patients with type 2 diabetes and even allowed some patients to wean off all anti-hyperglycemic medications. The investigators will conduct a follow-up study to determine the effects of whole fruit alone on glycemic control, liver fat, and cardiovascular risk factors. The study will be a single-arm controlled feeding study to determine the effects of eating a large amount of whole fruit for 17 weeks on glycemic control (Aim 1), liver fat (Aim 2a), and cardiovascular disease risk factors (Aim 2b) in patients with insulin-independent type 2 diabetes. The primary measures of glycemic control will be mean 24-hour glucose levels (as measured by continuous glucose monitoring) and mean 3-hour glucose levels (as measured during a 3-hour oral glucose tolerance test). These assessments will be supplemented by, and interpreted in light of, other glycemic outcomes, which are listed as outcomes #3-9 below.
By providing controlled, high-quality evidence, this study will determine whether whole fruit is good or bad for patients with type 2 diabetes and will improve dietary guidelines for the hundreds of millions of individuals with type 2 diabetes.
10,371 studies on the registry are indexed under Diabetes Mellitus, Type 2; 1,406 are open to participants now.
This study's planned enrollment of 25 is below the median of 80 across 8,350 interventional studies indexed under Diabetes Mellitus, Type 2.
Browse Diabetes Mellitus, Type 2 studies →Harvard School of Public Health (HSPH) is the lead sponsor of 154 studies on the registry; 10 are open to participants now.
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Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
A blood test of average blood sugar over the past two to three months, given as a percentage or in mmol/mol. 6.5% (48 mmol/mol) or more is the usual threshold for diabetes, normally confirmed by a second test.
A condition in which the immune system attacks the body’s own tissues, such as rheumatoid arthritis, lupus, psoriasis, type 1 diabetes or inflammatory bowel disease.
Immunotherapy studies often leave out active autoimmune disease, and some name exceptions, such as thyroid disease on replacement hormone. Check the exceptions this study lists.
GFR (glomerular filtration rate) is how much blood the kidneys filter each minute. It is usually estimated from a blood test — eGFR, by formulas such as CKD-EPI or MDRD — and some studies ask for it to be measured directly instead. Usually given in mL/min/1.73 m².
Check the method, the units and the minimum the study states. A value of 90 or above is in the normal-or-high range, but kidney damage can show in other tests too.
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
The protein in red blood cells that carries oxygen. A low level is anaemia, which can cause tiredness and breathlessness. Measured in g/dL or g/L (9 g/dL is 90 g/L).
HbA1c
A blood test of average blood sugar over the past two to three months, given as a percentage or in mmol/mol. 6.5% (48 mmol/mol) or more is the usual threshold for diabetes, normally confirmed by a second test.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Autoimmune disease
A condition in which the immune system attacks the body’s own tissues, such as rheumatoid arthritis, lupus, psoriasis, type 1 diabetes or inflammatory bowel disease.
Immunotherapy studies often leave out active autoimmune disease, and some name exceptions, such as thyroid disease on replacement hormone. Check the exceptions this study lists.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
GFR and eGFR (kidney filtering)
GFR (glomerular filtration rate) is how much blood the kidneys filter each minute. It is usually estimated from a blood test — eGFR, by formulas such as CKD-EPI or MDRD — and some studies ask for it to be measured directly instead. Usually given in mL/min/1.73 m².
Check the method, the units and the minimum the study states. A value of 90 or above is in the normal-or-high range, but kidney damage can show in other tests too.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Clinically significant
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hemoglobin (Hb)
The protein in red blood cells that carries oxygen. A low level is anaemia, which can cause tiredness and breathlessness. Measured in g/dL or g/L (9 g/dL is 90 g/L).
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Participants will consume a large amount of whole fruit, constituting 50% of total calories.
Other: Whole Fruit
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.
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).
Time frame: Change from baseline to week 17
Mean 3-hour Glucose Levels
Mean glucose (mg/dl) during a 3-hour oral glucose tolerance test (OGTT)
Time frame: Change from baseline to week 17
Mean 3-hour Insulin
Mean insulin (mU/l) during a 3-hour OGTT
Time frame: Change from baseline to week 17
Mean 3-hour C-Peptide
Mean C-Peptide (ng/ml) during a 3-hour OGTT
Time frame: 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
Time frame: 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
Time frame: 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.
Time frame: 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).
Time frame: 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.
Time frame: Change from baseline to week 17
Intrahepatic Lipid (Liver Fat)
Percentage as measured using Magnetic Resonance Spectroscopy (MRS) and 3-point M-Dixon Magnetic Resonance Imaging (MRI)
Time frame: Change from baseline to week 17
Body Weight
kg
Time frame: Change from baseline to week 17
Systolic and Diastolic Blood Pressure
mm Hg
Time frame: Change from baseline to week 17
Heart Rate
beats per minute
Time frame: Change from baseline to week 17
Lipids
Fasting total cholesterol (mg/dl), LDL cholesterol (mg/dl), HDL cholesterol (mg/dl), and triglycerides (mg/dl).
Time frame: Change from baseline to week 17
Plan to share: No
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