PrediabetesNCT07229781
Mediterranean Diet and Blood Sugar Study
A study testing Mediterranean-style diet with potatoes and Traditional-style Mediterranean diet in people with Prediabetes, run by Penn State University at 1 site in United States.
Trial summary
The purpose of this research study is to determine if a healthy Mediterranean diet containing one medium potato/day has equivalent or non-different effects on risk factors for type 2 diabetes and heart disease compared to a healthy Mediterranean diet without potatoes in adults with prediabetes. Read more about this study
- Who is it for?
- Ages 25 to 65 years
- Conditions the study is for
- Prediabetes
- What is being tested?
- Mediterranean-style diet with potatoes and Traditional-style Mediterranean diet
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 74 participants
- Where
- 1 siteUnited States
- Study dates
- 26 Aug 2026to 30 Apr 2028
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 25 to 65 years
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Age 25-65 years
- Prediabetes assessed by an HbA1c of 5.7-6.4% or fasting glucose 100-125 mg/dL at screening
- BMI 25-40 kg/m2 at screening
Who cannot join
- HbA1c ≥6.5% at screening
- LDL-C (calculated with the Martin-Hopkins equation) ≥190 mg/dL at screening
- Hemoglobin <13.2 g/dL at screening
- Fasting triglycerides >350 mg/dL at screening
- -≥10% change in body weight within the 6 months prior to enrollment
- Blood pressure >140/90 mmHg at screening
Show all 26Show fewer
- Type 1 or type 2 diabetes
- Prescription of anti-hypertensive, lipid-lowering, or glucose-lowering drugs
- Intake of supplements that affect the outcomes of interest (i.e., lipid, blood pressure, or glucose lowering; vitamin C or multi-vitamins containing vitamin C) and are unwilling to cease during the study period.
- History of liver, kidney, or autoimmune disease
- Prior cardiovascular event (e.g., stroke, heart attack)
- Current pregnancy or intention of pregnancy within the next 6 months
- Lactation within the prior 6 months
- Allergy/intolerance/sensitivity/dislike of any foods in the study menus
- Antibiotic use within the prior 1 month
- Oral steroid use within the prior 1 month
- Use of tobacco or nicotine-containing products within the past 6 months
- History of cancer at any site within the past 10 years (eligible if ≥10 years without recurrence) or non-melanoma skin cancer within the past 5 years (eligible if ≥5 years without recurrence)
- Participation in another clinical trial within 60 days of baseline
- Currently following a restricted or weight-loss diet
- Prior bariatric surgery
- Intake of >14 alcoholic drinks/week and/or not willing to avoid alcohol consumption for 48 hours prior to test visits
- Principal Investigator discretion related to the potential participant's ability to adhere to the study requirements, including being able to come to attend visits
- Does not speak and/or understand English
- Unwilling to refrain from donating blood during the study
- Weight <110 lb
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
United States1 site, 1 recruiting
- Recruiting
The Pennsylvania State University
University Park, Pennsylvania, 16802
Kristina Petersen, PhD, 814-865-7206, kup63@psu.edu
About this study
Official title: Glycemic Effects of a Mediterranean-Style Dietary Pattern Containing Potatoes in Adults With Prediabetes
The purpose of this research study is to determine if a healthy Mediterranean diet containing one medium potato/day has equivalent or non-different effects on risk factors for type 2 diabetes and heart disease compared to a healthy Mediterranean diet without potatoes in adults with prediabetes. Participants will be randomly assigned to one of the test diets and be asked to consume this diet for 12 weeks (84 days). Testing will be conducted at the beginning and end of the study.
Read the detailed description
This is a 12-week, 2-arm parallel, randomized controlled feeding trial. Participants will be randomized to either a Mediterranean-style diet that includes 1 medium potato/day/2000 kcal replacing some grains , or a traditional-style Mediterranean dietary pattern without potatoes. All food will be provided for the 12-week study duration.
- Conditions
- Prediabetes
- Being tested
- Mediterranean-style diet with potatoes, Traditional-style Mediterranean diet
- Keywords
- prediabetes, diet, nutrition, Mediterranean diet, cardiovascular disease
- Medical subject headings
- Prediabetic State, Cardiovascular Diseases
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Mediterranean-style diet with potatoesOther
The diet will contain 1 medium potato/day/2000 kcal
Traditional-style Mediterranean dietOther
Traditional-style Mediterranean diet higher in grains
| Study group | Role | What they receive |
|---|---|---|
| Mediterranean-style diet with potato (MED-P) | Experimental | Mediterranean-style diet that includes 1 medium potato/day/2000 kcal replacing some grains Receives: Other: Mediterranean-style diet with potatoes |
| Traditional-style Mediterranean dietary pattern (MED) | Active comparator | A traditional-style Mediterranean diet that does not contain potatoes (potatoes are not a defining feature of this diet) and is higher in grains. Receives: Other: Traditional-style Mediterranean diet |
What is being measured
The primary outcome is the main question the study is designed to answer.
Change in HbA1c
HbA1c will be assessed at baseline and 12-weeks and expressed as percentage . The change in HbA1c will be calculated by subtracting the baseline value from the 12 week value and expressed as percentage point change.
Measured: 12-weeks
Secondary outcomes (18)
Change in fasting glucose
Change in fasting plasma glucose expressed as mg/dL. Change in glucose will be calculated as the mean of the 12 week measures (i.e., mean of day 1 and day 2 values) minus the mean of the baseline measures (i.e., mean of day 1 and day 2 values).
Measured: 12-weeks
Change in mean glucose
Change in mean glucose assessed by a continuous glucose monitor (CGM) expressed as mg/dL. Change in mean glucose will be calculated as mean glucose assessed from 7 days of CGM wear at 12 weeks minus mean glucose assessed from 7 days of CGM wear at baseline.
Measured: 12-weeks
Change in mean time in range
Change in mean time in range (glucose 70-140 mg/dL) assessed by a continuous glucose monitor (CGM) expressed as minutes per day. Change in mean time in range will be calculated as mean time in range assessed from 7 days of CGM wear at 12 weeks minus mean time in range assessed from 7 days of CGM wear at baseline.
Measured: 12-weeks
Change in glycemic variability
Change in mean glycemic variability assessed by a continuous glucose monitor (CGM) expressed as the coefficient of variability. Change in mean glycemic variability will be calculated as mean glycemic variability assessed from 7 days of CGM wear at 12 weeks minus mean glycemic variability assessed from 7 days of CGM wear at baseline.
Measured: 12-weeks
Change in fasting insulin
Change in fasting serum insulin expressed as micro IU/mL. Change in insulin will be calculated as the mean of the 12 week measures (i.e., mean of day 1 and day 2 values) minus the mean of the baseline measures (i.e., mean of day 1 and day 2 values).
Measured: 12-weeks
Change in homeostatic model of insulin resistance (HOMA-IR)
Homeostatic model of insulin resistance (HOMA-IR) will be calculated from insulin and glucose measured from a fasting blood sample. Calculated as (insulin × glucose) / 22.5. Change in HOMA-IR will be calculated as the mean of the 12 week measures (i.e., mean of day 1 and day 2 values) minus the mean of the baseline measures (i.e., mean of day 1 and day 2 values).
Measured: 12-weeks
Change in LDL-Cholesterol
Assessed from fasting blood draw expressed in mg/dL. Change in LDL-cholesterol will be calculated as the mean of the 12-week measures (i.e., mean of day 1 and day 2 values) minus the mean of the baseline measures (i.e., mean of day 1 and day 2 values).
Measured: 12-weeks
Change in apolipoprotein B
Assessed from fasting blood draw expressed in mg/dL. Change in apolipoprotein B will be calculated by subtracting the baseline value from the 12 week value.
Measured: 12-weeks
Change in non-HDL cholesterol
Assessed from fasting blood draw expressed in mg/dL. Change in non-HDL cholesterol will be calculated as the mean of the 12-week measures (i.e., mean of day 1 and day 2 values) minus the mean of the baseline measures (i.e., mean of day 1 and day 2 values).
Measured: 12-weeks
Change in Total Cholesterol
Assessed from fasting blood draw expressed in mg/dL. Change in total cholesterol will be calculated as the mean of the 12-week measures (i.e., mean of day 1 and day 2 values) minus the mean of the baseline measures (i.e., mean of day 1 and day 2 values).
Measured: 12-weeks
Change in HDL-Cholesterol
Assessed from fasting blood draw expressed in mg/dL. Change in HDL-cholesterol will be calculated as the mean of the 12-week measures (i.e., mean of day 1 and day 2 values) minus the mean of the baseline measures (i.e., mean of day 1 and day 2 values).
Measured: 12-weeks
Change in Triglycerides
Assessed from fasting blood draw expressed in mg/dL. Change in triglycerides will be calculated as the mean of the 12-week measures (i.e., mean of day 1 and day 2 values) minus the mean of the baseline measures (i.e., mean of day 1 and day 2 values).
Measured: 12-weeks
Change in C-reactive protein
Assessed from fasting blood draw expressed in mg/L. Change in C-reactive protein will be calculated as the mean of the 12-week measures (i.e., mean of day 1 and day 2 values) minus the mean of the baseline measures (i.e., mean of day 1 and day 2 values).
Measured: 12-weeks
Change in Central Systolic and Diastolic Blood Pressure
Central blood pressure measured assessed using a SphymoCor Xcel (Atcor Medical) at baseline \& 12 weeks. Change will be calculated by subtracting the baseline value from the end point value.
Measured: 12-weeks
Change in Peripheral Systolic and Diastolic Blood Pressure
Peripheral blood pressure measured assessed using a SphymoCor Xcel (Atcor Medical) at baseline \& 12 weeks. Change will be calculated by subtracting the baseline value from the end point value.
Measured: 12-weeks
Change in Carotid-Femoral Pulse Wave Velocity
Measured assessed using a SphymoCor Xcel (Atcor Medical) at baseline \& 12 weeks. Change will be calculated by subtracting the baseline value from the end point value.
Measured: 12-weeks
Change in particle size and number of LDL, HDL, triglyceride rich lipoproteins
Measured via Nuclear Magnetic Resonance
Measured: 12-weeks
Diet Satisfaction
Participants will complete a survey that we have previously developed to assess diet satisfaction at 12 weeks.
Measured: 12-weeks
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted17 Nov 2025
- Study start26 Aug 2026
- Primary completion30 Apr 2028 (estimated)
- Study completion30 Apr 2028 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for PrediabetesStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Single blind
- Who is masked
- Outcomes assessor
- Enrolment
- 74 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Penn State University
- Sponsor type
- University, hospital or other
- Collaborators
- Alliance for Potato Research and Education
- Responsible party
- Principal investigator, Kristina Petersen PhD, APD, FAHA, Penn State University
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07229781
- Sponsor's protocol ID
- MDP
- Status last verified
- Oct 2026
- First submitted
- 13 Nov 2025
- Last updated
- 5 Oct 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Yes
Study at a glance
From the registry record, last updated by the sponsor on 5 Oct 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Glycemic Effects of a Mediterranean-Style Dietary Pattern Containing Potatoes in Adults With Prediabetes
- ClinicalTrials.gov ID
- NCT07229781
- Acronym / sponsor ID
- MDP
- Conditions
- Prediabetes
- Keywords
- prediabetes, diet, nutrition, Mediterranean diet, cardiovascular disease
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 74 participants (estimated)
- Lead sponsor
- Penn State UniversityUniversity, hospital or other
- Collaborators
- Alliance for Potato Research and Education
- Study start
- 26 Aug 2026 (actual)
- Primary completion
- 30 Apr 2028 (estimated)
- Study completion
- 30 Apr 2028 (estimated)
- First posted
- 17 Nov 2025 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The purpose of this research study is to determine if a healthy Mediterranean diet containing one medium potato/day has equivalent or non-different effects on risk factors for type 2 diabetes and heart disease compared to a healthy Mediterranean diet without potatoes in adults with prediabetes. Participants will be randomly assigned to one of the test diets and be asked to consume this diet for 12 weeks (84 days). Testing will be conducted at the beginning and end of the study.
Detailed description
This is a 12-week, 2-arm parallel, randomized controlled feeding trial. Participants will be randomized to either a Mediterranean-style diet that includes 1 medium potato/day/2000 kcal replacing some grains , or a traditional-style Mediterranean dietary pattern without potatoes. All food will be provided for the 12-week study duration.
Study design
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Single blind (outcomes assessor)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Mediterranean-style diet with potato (MED-P) | Experimental | Other: Mediterranean-style diet with potatoesMediterranean-style diet that includes 1 medium potato/day/2000 kcal replacing some grains |
| Traditional-style Mediterranean dietary pattern (MED) | Active comparator | Other: Traditional-style Mediterranean dietA traditional-style Mediterranean diet that does not contain potatoes (potatoes are not a defining feature of this diet) and is higher in grains. |
Who may qualify
- Ages
- 25 to 65 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (3 listed)
- Age 25-65 years
- Prediabetes assessed by an HbA1c of 5.7-6.4% or fasting glucose 100-125 mg/dL at screening
- BMI 25-40 kg/m2 at screening
Key exclusion criteria (26 listed)
- HbA1c ≥6.5% at screening
- LDL-C (calculated with the Martin-Hopkins equation) ≥190 mg/dL at screening
- Hemoglobin <13.2 g/dL at screening
- Fasting triglycerides >350 mg/dL at screening
- -≥10% change in body weight within the 6 months prior to enrollment
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Mediterranean-style diet with potatoesThe diet will contain 1 medium potato/day/2000 kcal | Other | Mediterranean-style diet with potato (MED-P) |
| Traditional-style Mediterranean dietTraditional-style Mediterranean diet higher in grains | Other | Traditional-style Mediterranean dietary pattern (MED) |
Primary outcome
Change in HbA1c
Time frame: 12-weeks
HbA1c will be assessed at baseline and 12-weeks and expressed as percentage . The change in HbA1c will be calculated by subtracting the baseline value from the 12 week value and expressed as percentage point change.
18 secondary outcomes
Change in fasting glucose
Time frame: 12-weeks
Change in mean glucose
Time frame: 12-weeks
Change in mean time in range
Time frame: 12-weeks
Change in glycemic variability
Time frame: 12-weeks
Change in fasting insulin
Time frame: 12-weeks
Change in homeostatic model of insulin resistance (HOMA-IR)
Time frame: 12-weeks
Change in LDL-Cholesterol
Time frame: 12-weeks
Change in apolipoprotein B
Time frame: 12-weeks
Change in non-HDL cholesterol
Time frame: 12-weeks
Change in Total Cholesterol
Time frame: 12-weeks
Change in HDL-Cholesterol
Time frame: 12-weeks
Change in Triglycerides
Time frame: 12-weeks
Change in C-reactive protein
Time frame: 12-weeks
Change in Central Systolic and Diastolic Blood Pressure
Time frame: 12-weeks
Change in Peripheral Systolic and Diastolic Blood Pressure
Time frame: 12-weeks
Change in Carotid-Femoral Pulse Wave Velocity
Time frame: 12-weeks
Change in particle size and number of LDL, HDL, triglyceride rich lipoproteins
Time frame: 12-weeks
Diet Satisfaction
Time frame: 12-weeks
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 5 Oct 2026.
- Individual participant dataSharing planned: Yes
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Mediterranean-style diet with potatoes and Traditional-style Mediterranean diet in people with Prediabetes, run by Penn State University at 1 site in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 3 inclusion and 26 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 5 Oct 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Kristina Petersen, PhD (814-865-7206, kup63@psu.edu), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Change in HbA1c (time frame: 12-weeks). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 5 Oct 2026.