PrediabetesPhase 3D2d-TTTNCT07448974
Vitamin D and Type 2 Diabetes - Treat-To-Target
A Phase 3 study testing Vitamin D (Cholecalciferol ) in people with Prediabetes and Type 2 Diabetes (T2DM), run by Tufts Medical Center at 1 site in United States.
Trial summary
This study tests whether taking a weekly dose of vitamin D, with the dose adjusted to reach a target blood vitamin D level, can help control blood sugar levels in adults at high risk of developing type 2 diabetes (prediabetes). Research suggests that vitamin D may play a role in blood sugar control. Read more about this study
- Who is it for?
- Ages 30 to 74 years
- Conditions the study is for
- Prediabetes, Type 2 Diabetes (T2DM)
- What is being tested?
- Vitamin D (Cholecalciferol )
- Type of treatment
- Pill or oral medicine
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 100 participants
- Where
- 1 siteUnited States
- Study dates
- 4 Aug 2026to Mar 2031
- Phase
- Phase 3
- 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 30 to 74 years
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- High-risk prediabetes ("at high risk for type 2 diabetes") defined by meeting the following 2 prediabetes criteria established by the American Diabetes Association (ADA) in the 2010 clinical practice guidelines:
- Fasting plasma glucose (FPG) 100-125 mg/dL, inclusive
- Hemoglobin A1c (HbA1c) 5.7-6.4%, inclusive
- Age 30-74 years, inclusive
- Body Mass Index ≥ 23.0 and ≤ 35.0 kg/m2
- Provision of signed and dated written informed consent prior to any study procedures.
Who cannot join
- History of diabetes (ICD10 diabetes code E08.X through E13.X) or meeting a diabetes glycemic criterion at screening, as defined by the ADA guidelines (FPG ≥ 126 mg/dL or HbA1c ≥ 6.5%).
- History (past 2 years) of hyperparathyroidism, symptomatic or asymptomatic (i.e., radiographic) nephrolithiasis or hypercalcemia.
- Any medical condition (past 2 years) that in the opinion of the site investigator may increase risk for nephrolithiasis or hypercalcemia during the trial (e.g., sarcoidosis).
- If older than 70 years, history (past 1 year) of a fall.
- Use of tanning devices within 12 weeks of the baseline visit and unwilling to stop use of tanning devices for the duration of the study.
- Medications and Supplements
Show all 47Show fewer
- Use (past 6 months) of hypoglycemic pharmacotherapy (oral or injectable medication approved by the FDA for type 2 diabetes) for any condition (e.g., prediabetes, diabetes, polycystic ovarian syndrome, MASLD, sleep apnea) or any other medication that may affect glycemia (e.g., hydroxychloroquine)
- Current use of medications approved by the FDA for weight management (e.g., incretin receptor agonists) or planned use during the study.
- Use of supplements containing vitamin D at total doses higher than 1000 IU/day within 8 weeks of the baseline visit and unwillingness to limit vitamin D supplementation dosage to no higher than 1000 IU/day during the study. Because supplements vary widely in vitamin D content (e.g., may include cod liver or cod liver oi), participants will bring all supplements to the site for a review by the research team.
- Use of supplements containing calcium at total doses higher than 600 mg/day within 1 week of the baseline visit and unwillingness to limit calcium supplementation dosage to no higher than 600 mg/day during the study.
- Current use of medications or conditions (e.g., untreated celiac disease) that would interfere with the absorption or metabolism of vitamin D.
- Use of an anticonvulsant drug started within 6 months of screening. Stable regimen of anticonvulsants is allowed.
- History of intolerance to vitamin D supplements, allergic to any content of the study drug or unwilling to take vitamin D supplements (e.g., someone who eats a vegan diet and would object to the cholecalciferol ingredient which is produced from cholesterol extracted from sheep wool harvested from healthy living sheep).
- Other Medical History
- Severe symptomatic cardiovascular disease based on history (unstable angina, dyspnea on exertion, paroxysmal nocturnal dyspnea, arrhythmia, congestive heart failure NYHA class II or higher, claudication)
- History (past 1 year) of myocardial infarction, percutaneous coronary intervention, or coronary artery bypass graft.
- History (past 1 year) of cerebrovascular disease (stroke, transient ischemic attack).
- Any type of cancer (past 5 years) except for basal cell skin cancer. Prostate cancer (for men over age 55) or well-differentiated thyroid cancer not expected to require treatment (except for suppression with thyroid hormone) over the next 3 years, are not exclusions. People with history of squamous cell cancer of the skin, which was completely excised and with no evidence of metastases, are eligible.
- History (past 6 months) of treatment with oral (for > 7 days) or intravenous glucocorticoids or disease likely to require oral or intravenous glucocorticoid therapy during the study. Inhaled glucocorticoid use is not an exclusion. Epidural or intra-articular glucocorticoid injections are not exclusions, but study visits need to be conducted at least two weeks after the injection. Persons with adrenal insufficiency treated with physiologic doses of glucocorticoids who are otherwise stable are not excluded.
- History (past 1 year) of substance abuse or unstable psychiatric disorder that in the opinion of the site investigator would impede competence or adherence with study procedures or hinder completion of the study or increase risk.
- History of bariatric surgery (e.g., Roux-en-Y gastric bypass, gastric sleeve) or planned bariatric surgery in the next 2 years.
- Extreme (over 18 hours) intermittent fasting diets because prolonged fasting downregulates CYP2R1 activity.
- A life-threatening event within 30 days of screening or currently planned major surgery.
- Any other active medical condition (including but not limited to liver disease, wasting illness, HIV, tuberculosis, oxygen-dependent chronic obstructive pulmonary disease, organ transplant, Cushing's syndrome) that in the opinion of the site investigators would interfere with the study objectives, impede competence or adherence with study procedures or increase risk.
- Uncontrolled hypertension (systolic blood pressure > 160 mm Hg or diastolic blood pressure > 100 mm Hg).
- Poor venous access.
- Laboratory Evaluation
- Serum liver transaminase higher than 3 times the normal range for the clinical site's laboratory, within 18 months of screening.
- Anemia (hematocrit < 32 for women, < 36 for men), whole blood transfusion (within 18 months of screening) or chronic requirement, whole blood donation (within 3 months of screening) or other condition (hemolysis, hemoglobinopathy) rendering HbA1c results unreliable as indicator of chronic glycemia. Participants who donate platelets are not excluded.
- Low platelet count (< 100,000) within 18 months of screening.
- Chronic kidney disease, defined as estimated glomerular filtration rate [GFR] < 50 mL/min per 1.73 m2 from creatinine level and GFR calculated by the new Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations that omit race within 18 months of screening.
- Hypercalcemia, defined as serum calcium concentration ≥ upper limit of normal within 18 months of screening.
- Hypercalciuria, defined as spot urine (morning void) calcium-creatinine ratio > 0.275 within 18 months of screening.
- Baseline serum 25(OH)D level greater than 100 ng/mL.
- Other
- Participation (within 30 days of screening) in another interventional research study, and unwillingness to refrain from participating in another intervention study during the study.
- Previous randomization in the study. Participants who did not qualify after screening may be screened again if the prior reason for exclusion has been addressed (e.g., high blood pressure is treated).
- Any other reason that in the opinion of the site investigator would interfere with the study objectives, impede adherence with study procedures or hinder completion of the study or increase risk.
- Women only
- Pregnancy (past 1 year by report or positive pregnancy test at screening), intent to become pregnant in the next 2 years. History of gestational diabetes is not an exclusion criterion.
- Currently breastfeeding.
- Use of oral contraceptives or menopausal hormone therapy started within 3 months of baseline. .
- Continuous Glucose Monitoring specific
- Regular use of personal CGM and unwillingness to refrain from using personal CGM for the duration of the study.
- Use of hydroxyurea or regular use of high doses of acetaminophen (may impact CGM).
- Extensive skin changes (e.g., skin breakdown, rash) making CGM sensor use problematic.
- Significant skin sensitivity to adhesive (making CGM sensor unfeasible).
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Tufts Medical Center Endocrine Research Team contact
United States1 site, 1 recruiting
- Recruiting
Tufts Medical Center
Boston, Massachusetts, 02111
Tufts Medical Center Endocrine Research Team, 617-636-3232, endocrine-research@tuftsmedicine.org
Anastassios Pittas, MD
About this study
Official title: Vitamin D and Type 2 Diabetes, Treat-To-Target
This study tests whether taking a weekly dose of vitamin D, with the dose adjusted to reach a target blood vitamin D level, can help control blood sugar levels in adults at high risk of developing type 2 diabetes (prediabetes).
Research suggests that vitamin D may play a role in blood sugar control. The goal of this study is to see whether adjusting the dose of vitamin D to reach a specific blood vitamin D level improves blood sugar control compared with a placebo (a look-alike pill without vitamin D).
Read more
One hundred adults aged 30 to 74 with prediabetes will take part. Participants will be randomly assigned (by chance) to receive either weekly vitamin D supplements or a placebo. Neither the participants nor the research team will know which group a participant is in during the study.
Participants in the vitamin D group will start with one specific dose. After three months, a blood test will be used to decide whether the dose should stay the same or be increased to reach the target vitamin D level. Participants in the placebo group will continue taking the placebo each week.
All participants will be followed for about 18 months. During the study, they will attend scheduled study visits, have blood tests, and wear a continuous glucose monitor, a small device that measures blood sugar levels throughout the day and night. The research team will also make periodic phone calls to check on health changes, medication use, and study participation.
The main outcome of the study is the proportion of time that the participants' blood sugar levels remains in a healthy range.
- Conditions
- Prediabetes, Type 2 Diabetes (T2DM)
- Being tested
- Vitamin D (Cholecalciferol ), Placebo
- Keywords
- vitamin D, cholecalciferol, continuous glucose monitoring, diabetes prevention, prediabetes, type 2 diabetes
- Medical subject headings
- Prediabetic State, Diabetes Mellitus, Type 2
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Vitamin D (Cholecalciferol )Drug
Vitamin D (cholecalciferol) will be administered orally once weekly for approximately 18 months. The vitamin D will be provided in liquid form in an ampule. Participants in the intervention group will begin with a dose of 25,000 IU per week. A blood vitamin D level will be measured at 3 months, and the dose will be increased to 50,000 IU per week for participants whose results are below the study target.
PlaceboDrug
Placebo will be administered orally once weekly for approximately 18 months. The placebo will be provided in an ampule and will be matched in appearance, dosing schedule, and duration to the active study medication.
| Study group | Role | What they receive |
|---|---|---|
| Vitamin D | Active comparator | Participants will receive oral vitamin D (cholecalciferol) once weekly throughout the study. Receives: Drug: Vitamin D (Cholecalciferol ) |
| Placebo | Placebo comparator | Participants in this arm will receive an oral placebo taken once weekly throughout the study. Receives: Drug: Placebo |
What is being measured
The primary outcome is the main question the study is designed to answer.
Time-in-normoglycemia 140
The cumulative proportion of time that a participant's glucose level is below 140 mg/dL at each CGM measurement period.
Measured: Assessed every 6 months from enrollment to the end of the study at 18 months.
Time-In-Normoglycemia 126
The cumulative proportion of time that a participant's glucose level is below 126 mg/dL at each CGM measurement period.
Measured: Assessed every 6 months from enrollment to the end of the study at 18 months.
Secondary outcomes (7)
Mean glycemia (mg/dL)
The average glucose level at each CGM measurement period.
Measured: Assessed every 6 months from enrollment to the end of the study at 18 months
Glycemic variability
Glycemic variability will be assessed using the mean amplitude of glycemic excursions at each CGM measurement period.
Measured: Assessed every 6 months from enrollment to the end of the study at 18 months
Hemoglobin A1c (%)
Measured: Assessed every 6 months from enrollment to the end of the study at 18 months.
Fasting plasma glucose (mg/dL)
Measured: Assessed every 6 months from enrollment to the end of the study at 18 months.
Atherosclerotic cardiovascular risk
Atherosclerotic cardiovascular risk, assessed by the PREVENT risk calculator. The calculator requires a lipid profile and a urine albumin creatinine ratio. Higher PREVENT values generally indicate higher estimated cardiovascular risk.
Measured: Assessed at baseline, month 12 and month 18
Hypercalcemia
Measured: Assessed every 6 months from enrollment to the end of the study at 18 months.
Hypercalciuria
Measured: Assessed every 6 months from enrollment to the end of the study at 18 months.
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted4 Mar 2026
- Study start4 Aug 2026
- Primary completionMar 2030 (estimated)
- Study completionMar 2031 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (3)Papers the sponsor has linked to this study.
- 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 3
- Primary purpose
- Other
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Quadruple blind
- Who is masked
- Participant, Care provider, Investigator, Outcomes assessor
- Enrolment
- 100 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Tufts Medical Center
- Sponsor type
- University, hospital or other
- Collaborators
- Abiogen Pharma
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07448974
- Sponsor's protocol ID
- D2d-TTT
- Acronym
- D2d-TTT
- Status last verified
- Aug 2026
- First submitted
- 16 Jan 2026
- Last updated
- 18 Aug 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
- Individual data sharing
- Yes: Consistent with the International Committee of Medical Journal Editors (ICMJE) policy, we will make de-identified individual participant data available, following publication, upon reasonable request to qualified investigators who provide a methodologically sound proposal and agree to a data use agreement to protect participant confidentiality. A data dictionary (a description of the variables collected for each individual) will be provided so that the data can be fully interpreted.
Publications
Chatterjee R, Davenport CA, Vickery EM, Johnson KC, Kashyap SR, LeBlanc ES, Nelson J, Dagogo-Jack S, Pittas AG, Hughes BD; D2d Research Group. Effect of intratrial mean 25(OH)D concentration on diabetes risk, by race and weight: an ancillary analysis in the D2d study. Am J Clin Nutr. 2023 Jul;118(1):59-67. doi: 10.1016/j.ajcnut.2023.03.021. Epub 2023 Mar 29.
PubMed 37001590Pittas AG, Kawahara T, Jorde R, Dawson-Hughes B, Vickery EM, Angellotti E, Nelson J, Trikalinos TA, Balk EM. Vitamin D and Risk for Type 2 Diabetes in People With Prediabetes : A Systematic Review and Meta-analysis of Individual Participant Data From 3 Randomized Clinical Trials. Ann Intern Med. 2023 Mar;176(3):355-363. doi: 10.7326/M22-3018. Epub 2023 Feb 7.
PubMed 36745886Pittas AG, Dawson-Hughes B, Sheehan P, Ware JH, Knowler WC, Aroda VR, Brodsky I, Ceglia L, Chadha C, Chatterjee R, Desouza C, Dolor R, Foreyt J, Fuss P, Ghazi A, Hsia DS, Johnson KC, Kashyap SR, Kim S, LeBlanc ES, Lewis MR, Liao E, Neff LM, Nelson J, O'Neil P, Park J, Peters A, Phillips LS, Pratley R, Raskin P, Rasouli N, Robbins D, Rosen C, Vickery EM, Staten M; D2d Research Group. Vitamin D Supplementation and Prevention of Type 2 Diabetes. N Engl J Med. 2019 Aug 8;381(6):520-530. doi: 10.1056/NEJMoa1900906. Epub 2019 Jun 7.
PubMed 31173679
Study at a glance
From the registry record, last updated by the sponsor on 18 Aug 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Vitamin D and Type 2 Diabetes, Treat-To-Target
- ClinicalTrials.gov ID
- NCT07448974
- Acronym / sponsor ID
- D2d-TTT / D2d-TTT
- Conditions
- Prediabetes, Type 2 Diabetes (T2DM)
- Keywords
- vitamin D, cholecalciferol, continuous glucose monitoring, diabetes prevention, prediabetes, type 2 diabetes
- Phase
- Phase 3
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 100 participants (estimated)
- Lead sponsor
- Tufts Medical CenterUniversity, hospital or other
- Collaborators
- Abiogen Pharma
- Study start
- 4 Aug 2026 (actual)
- Primary completion
- Mar 2030 (estimated)
- Study completion
- Mar 2031 (estimated)
- First posted
- 4 Mar 2026 (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.
This study tests whether taking a weekly dose of vitamin D, with the dose adjusted to reach a target blood vitamin D level, can help control blood sugar levels in adults at high risk of developing type 2 diabetes (prediabetes).
Research suggests that vitamin D may play a role in blood sugar control. The goal of this study is to see whether adjusting the dose of vitamin D to reach a specific blood vitamin D level improves blood sugar control compared with a placebo (a look-alike pill without vitamin D).
One hundred adults aged 30 to 74 with prediabetes will take part. Participants will be randomly assigned (by chance) to receive either weekly vitamin D supplements or a placebo. Neither the participants nor the research team will know which group a participant is in during the study.
Participants in the vitamin D group will start with one specific dose. After three months, a blood test will be used to decide whether the dose should stay the same or be increased to reach the target vitamin D level. Participants in the placebo group will continue taking the placebo each week.
All participants will be followed for about 18 months. During the study, they will attend scheduled study visits, have blood tests, and wear a continuous glucose monitor, a small device that measures blood sugar levels throughout the day and night. The research team will also make periodic phone calls to check on health changes, medication use, and study participation.
The main outcome of the study is the proportion of time that the participants' blood sugar levels remains in a healthy range.
Study design
- Primary purpose
- Other
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Quadruple blind (participant, care provider, investigator, outcomes assessor)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Vitamin D | Active comparator | Drug: Vitamin D (Cholecalciferol )Participants will receive oral vitamin D (cholecalciferol) once weekly throughout the study. |
| Placebo | Placebo comparator | Drug: PlaceboParticipants in this arm will receive an oral placebo taken once weekly throughout the study. |
Who may qualify
- Ages
- 30 to 74 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (6 listed)
- High-risk prediabetes ("at high risk for type 2 diabetes") defined by meeting the following 2 prediabetes criteria established by the American Diabetes Association (ADA) in the 2010 clinical practice guidelines:
- Age 30-74 years, inclusive
- Body Mass Index ≥ 23.0 and ≤ 35.0 kg/m2
- Provision of signed and dated written informed consent prior to any study procedures.
Key exclusion criteria (47 listed)
- History of diabetes (ICD10 diabetes code E08.X through E13.X) or meeting a diabetes glycemic criterion at screening, as defined by the ADA guidelines (FPG ≥ 126 mg/dL or HbA1c ≥ 6.5%).
- History (past 2 years) of hyperparathyroidism, symptomatic or asymptomatic (i.e., radiographic) nephrolithiasis or hypercalcemia.
- Any medical condition (past 2 years) that in the opinion of the site investigator may increase risk for nephrolithiasis or hypercalcemia during the trial (e.g., sarcoidosis).
- If older than 70 years, history (past 1 year) of a fall.
- Use of tanning devices within 12 weeks of the baseline visit and unwilling to stop use of tanning devices for the duration of the study.
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 |
|---|---|---|
| Vitamin D (Cholecalciferol )Vitamin D (cholecalciferol) will be administered orally once weekly for approximately 18 months. The vitamin D will be provided in liquid form in an ampule. Participants in the intervention group will begin with a dose of 25,000 IU per week. A blood vitamin D level will be measured at 3 months, and the dose will be increased to 50,000 IU per week for participants whose results are below the study target. | Drug | Vitamin D |
| PlaceboPlacebo will be administered orally once weekly for approximately 18 months. The placebo will be provided in an ampule and will be matched in appearance, dosing schedule, and duration to the active study medication. | Drug | Placebo |
Primary outcome
Time-in-normoglycemia 140
Time frame: Assessed every 6 months from enrollment to the end of the study at 18 months.
The cumulative proportion of time that a participant's glucose level is below 140 mg/dL at each CGM measurement period.
Time-In-Normoglycemia 126
Time frame: Assessed every 6 months from enrollment to the end of the study at 18 months.
The cumulative proportion of time that a participant's glucose level is below 126 mg/dL at each CGM measurement period.
7 secondary outcomes
Mean glycemia (mg/dL)
Time frame: Assessed every 6 months from enrollment to the end of the study at 18 months
Glycemic variability
Time frame: Assessed every 6 months from enrollment to the end of the study at 18 months
Hemoglobin A1c (%)
Time frame: Assessed every 6 months from enrollment to the end of the study at 18 months.
Fasting plasma glucose (mg/dL)
Time frame: Assessed every 6 months from enrollment to the end of the study at 18 months.
Atherosclerotic cardiovascular risk
Time frame: Assessed at baseline, month 12 and month 18
Hypercalcemia
Time frame: Assessed every 6 months from enrollment to the end of the study at 18 months.
Hypercalciuria
Time frame: Assessed every 6 months from enrollment to the end of the study at 18 months.
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 18 Aug 2026.
- Background: PubMed 37001590Chatterjee R, Davenport CA, Vickery EM, Johnson KC, Kashyap SR, LeBlanc ES, Nelson J, Dagogo-Jack S, Pittas AG, Hughes BD; D2d Research Group. Effect of intratrial mean 25(OH)D concentration on diabetes risk, by race and weight: an ancillary analysis in the D2d study. Am J Clin Nutr. 2023 Jul;118(1):59-67. doi: 10.1016/j.ajcnut.2023.03.021. Epub 2023 Mar 29.
- Background: PubMed 36745886Pittas AG, Kawahara T, Jorde R, Dawson-Hughes B, Vickery EM, Angellotti E, Nelson J, Trikalinos TA, Balk EM. Vitamin D and Risk for Type 2 Diabetes in People With Prediabetes : A Systematic Review and Meta-analysis of Individual Participant Data From 3 Randomized Clinical Trials. Ann Intern Med. 2023 Mar;176(3):355-363. doi: 10.7326/M22-3018. Epub 2023 Feb 7.
- Background: PubMed 31173679Pittas AG, Dawson-Hughes B, Sheehan P, Ware JH, Knowler WC, Aroda VR, Brodsky I, Ceglia L, Chadha C, Chatterjee R, Desouza C, Dolor R, Foreyt J, Fuss P, Ghazi A, Hsia DS, Johnson KC, Kashyap SR, Kim S, LeBlanc ES, Lewis MR, Liao E, Neff LM, Nelson J, O'Neil P, Park J, Peters A, Phillips LS, Pratley R, Raskin P, Rasouli N, Robbins D, Rosen C, Vickery EM, Staten M; D2d Research Group. Vitamin D Supplementation and Prevention of Type 2 Diabetes. N Engl J Med. 2019 Aug 8;381(6):520-530. doi: 10.1056/NEJMoa1900906. Epub 2019 Jun 7.
- Related InfoLink provided by the sponsor.
- Individual participant dataSharing planned: Yes. Consistent with the International Committee of Medical Journal Editors (ICMJE) policy, we will make de-identified individual participant data available, following publication, upon reasonable request to qualified investigators who provide a methodologically sound proposal and agree to a data use agreement to protect participant confidentiality. A data dictionary (a description of the variables collected for each individual) will be provided so that the data can be fully interpreted.
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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.
Tufts Medical Center Endocrine Research Team contact
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 3 study testing Vitamin D (Cholecalciferol ) in people with Prediabetes and Type 2 Diabetes (T2DM), run by Tufts Medical Center 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 6 inclusion and 47 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 18 Aug 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. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Phase 3 studies compare the treatment with the current standard treatment or a placebo in a large group, to confirm how well it works and watch for side effects.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
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 Tufts Medical Center Endocrine Research Team (617-636-3232, endocrine-research@tuftsmedicine.org), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Time-in-normoglycemia 140 (time frame: Assessed every 6 months from enrollment to the end of the study at 18 months.). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT07448974, which also lists 3 linked publications.
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 18 Aug 2026.