A Phase 3 interventional study of Vitamin D (Cholecalciferol ) and Placebo in Prediabetes and Type 2 Diabetes (T2DM), sponsored by Tufts Medical Center. Recruiting at 1 site in United States. Open to participants aged 30 Years to 74 Years. Per ClinicalTrials.gov, last updated 2026-08-18.
Sponsored by Tufts Medical Center · Phase 3, Interventional, and Other
Among 390 studies in Prediabetic State with a site in United States — 84 open to participants now, 108 under way, 2 of them phase 3. Prediabetic State · United States.
Among the 390 studies in Prediabetic State with a site in United States, this one is the 95th largest by planned enrollment of the 362 interventional ones that give a count, is one of 39 that started in 2026, is one of 16 in phase 3, reaches primary completion later than 104 of the 107 other live ones, and was the 360th registered.
918 studies on the registry are indexed under Prediabetic State; 232 are open to participants now.
Browse Prediabetic State studies →84 of the 390 studies in Prediabetic State with a site in United States are open now. Recruiting first, the newest first:
Rahul Sachdeva · Sites in United States
Ages 18+ · Healthy volunteers
University of South Florida · Sites in United States
Ages 18–70
St. Louis University · Sites in United States
Ages 18–69
Morehouse School of Medicine · Sites in United States
Ages 12+ · Healthy volunteers
Penn State University · Sites in United States
Ages 25–65
A study can be open while its sites in United States have not opened yet or have stopped. Only those recruiting at a site in United States →
Of the 145 Prediabetic State studies recruiting now, 51 (35%) set no upper age limit and 84 (58%) stop at 75 or younger; 12 take children under 18; 54 take healthy volunteers.
This study: 30 Years to 74 Years · all sexes · no healthy volunteers.
The full table on the hub →This tab as a report to print or save as PDF → With an account.
390 studies; the count open now beside each. This study's row is marked.
A study in two phases is counted once above. Listed by phase, each with its combined phases: Phase 1 22 · Phase 2 25 · Phase 3 16 · Phase 4 16
First in 1996; this study’s year is marked. 39 started in 2026.
By drug class, each counting the studies that test any of its medicines:
This study's planned enrollment of 100 is above the median of 62 across 762 interventional studies indexed under Prediabetic State.
Median enrollment 54 across the 362 interventional studies, 188 across the 28 observational. Of the 257 that completed or were terminated, 89 (35%) have results posted.
This tab as a report to print or save as PDF → With an account.
35 of 390 have an industry lead sponsor. The 10 most frequent:
Tufts Medical Center is the lead sponsor of 200 studies on the registry; 27 are open to participants now.
Of its 32 completed or terminated interventional studies of FDA-regulated products, 16 (50%) have results posted.
Tufts Medical Center has 4 studies filed under Prediabetic State — fewer than ten, so there is no comparison to draw.
45 of the studies in Prediabetic State with a site in United States that are under way reach primary completion within a year, 0 of them phase 3. Phase 3 first, then by date:
| Study | Primary completion |
|---|---|
| NCT06995378University of California, Los AngelesStudy EHR Risk Stratification Tools | 2026-11 |
| NCT05165706Stanford UniversityLongitudinal Multi-Omic Profiles to Reveal Mechanisms of Obesity-Mediated Insulin Resistance | 2026-11-30 |
| NCT07450118University of DelawareNested Pilot Study Comparing Two Treatments to Reduce Type 2 Diabetes Risk in At-Risk Delawareans | 2026-12 |
| NCT05067621Yale UniversitySemaglutide Effects in Obese Youth With Prediabetes/New Onset Type 2 Diabetes and Metabolic Dysfunction-Associated Steatotic Liver Disease | 2026-12 |
| NCT07868432Tufts UniversityGlycemic Impact of NNS Via the Gut Microbiome | 2026-12 |
Add all 45 to your calendar (.ics) → With an account.
Among the 390 studies in Prediabetic State with a site in United States, from their registry updates:
This tab as a report to print or save as PDF → With an account.
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.
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.
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:
Exclusion Criteria:
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
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
Poor venous access.
Laboratory Evaluation
Baseline serum 25(OH)D level greater than 100 ng/mL.
Other
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
Use of oral or menopausal hormone therapy started within 3 months of baseline. .
Continuous Glucose Monitoring specific
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.
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
The New York Heart Association’s four classes of how much heart failure limits physical activity.
Studies set their own limit — many outside heart failure leave out class III–IV, while heart failure studies may ask for a particular class. Check the class this study names.
A “mini-stroke”: temporary stroke-like symptoms caused by reduced blood flow to part of the brain, spinal cord or eye, without signs of a new stroke on a scan.
Stroke symptoms need emergency care at once, even if they go away.
Cancer that has spread from where it began to other parts of the body. “Metastatic” cancer is cancer that has spread this way.
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Chronic obstructive pulmonary disease: long-term lung disease that makes it hard to breathe out, including emphysema and chronic bronchitis.
Blood cells that help blood clot. Too few raises the risk of bleeding and bruising. A usual adult range is about 150–400 × 10⁹/L (150,000–400,000 per µL); each lab has its own reference range.
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.
The top of the normal range for a blood test, as set by the laboratory that runs it. Each lab prints its own range next to your result.
“≤ 2.5 × ULN” means the result can be up to two and a half times that top value.
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
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.
BMI (body mass index)
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
NYHA class (heart failure)
The New York Heart Association’s four classes of how much heart failure limits physical activity.
Studies set their own limit — many outside heart failure leave out class III–IV, while heart failure studies may ask for a particular class. Check the class this study names.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
TIA (transient ischaemic attack)
A “mini-stroke”: temporary stroke-like symptoms caused by reduced blood flow to part of the brain, spinal cord or eye, without signs of a new stroke on a scan.
Stroke symptoms need emergency care at once, even if they go away.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Metastases
Cancer that has spread from where it began to other parts of the body. “Metastatic” cancer is cancer that has spread this way.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Corticosteroids (steroids)
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
HIV
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
COPD
Chronic obstructive pulmonary disease: long-term lung disease that makes it hard to breathe out, including emphysema and chronic bronchitis.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Platelets
Blood cells that help blood clot. Too few raises the risk of bleeding and bruising. A usual adult range is about 150–400 × 10⁹/L (150,000–400,000 per µL); each lab has its own reference range.
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.
ULN (upper limit of normal)
The top of the normal range for a blood test, as set by the laboratory that runs it. Each lab prints its own range next to your result.
“≤ 2.5 × ULN” means the result can be up to two and a half times that top value.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraception
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Participants will receive oral vitamin D (cholecalciferol) once weekly throughout the study.
Drug: Vitamin D (Cholecalciferol )
Participants in this arm will receive an oral placebo taken once weekly throughout the study.
Drug: Placebo
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.
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.
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.
Time frame: 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.
Time frame: Assessed every 6 months from enrollment to the end of the study at 18 months.
Mean glycemia (mg/dL)
The average glucose level at each CGM measurement period.
Time frame: 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.
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
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.
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.
Insulin resistance
Insulin resistance by the homeostasis model assessment (HOMA-IR). Higher HOMA-IR values generally indicate greater estimated insulin resistance.
Time frame: Assessed at baseline, 12 months, and 18 months.
Insulin secretion
Insulin secretion by the homeostasis model assessment (HOMA-beta). Higher HOMA beta values generally indicate greater estimated pancreatic β-cell insulin secretion.
Time frame: Assessed from enrollment to the end of study at 18 months.
Plan to share: 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.
Started Aug 2026 (actual). Primary completion is estimated for Mar 2030, 43 months after the start.
Of 18 phase 3 interventional studies under Prediabetic State, half reached primary completion within 28 months of starting (the median), counting those still running; a quarter within 18 and three quarters within 40. This study's planned 43 months is above that.
How these figures are worked out, and which studies are left out of them.
Eligibility is decided by the study team. Share this record with your doctor or contact the team directly.
Contact study teamGet an email when the registry record changes — status, dates, results — or when someone posts here.
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Studies of the drug tested here: Vitamin D