The D2d Story

D2d has been a long journey that started in 2002 when the idea was conceived. Please explore how the D2d story has evolved throughout the years below.

2021


D2d Publication: Effect of Vitamin D Supplementation on Kidney Function in Adults with Prediabetes: A Secondary Analysis of a Randomized Trial
Despite evidence for associations between low circulating 25(OH)D concentration and kidney disease, few clinical trials have evaluated the effect of vitamin D supplementation on kidney...

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D2d Publication: Vitamin D Supplementation for Prevention of Cancer: The D2d Cancer Outcomes (D2dCA) Ancillary Study
Observational studies suggest that low vitamin D status may be a risk factor for cancer. In a population with prediabetes and overweight/obesity that is at...

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2020


Vitamin D Supplementation for Prevention of Type 2 Diabetes Mellitus: To D or Not to D?
The manuscript explains that results from recent trials are congruent with a large body of evidence from observational studies indicating that vitamin D has a role...

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D2d Publication: Intratrial Exposure to Vitamin D and New-Onset Diabetes Among Adults With Prediabetes: A Secondary Analysis From the Vitamin D and Type 2 Diabetes (D2d) Study
The manuscript explains how postrandomization biases may influence the estimate of efficacy of supplemental vitamin D in diabetes prevention trials. In the Vitamin D and...

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Untangling the Gordian Knot of Vitamin D Supplementation and Type 2 Diabetes Prevention
In the commentary Dr. Pittas and Dr. Balk explain that although meta-analyses increase statistical power, allowing more precise effect estimates, for them to be credible...

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D2d Publication: Implications of the Hemoglobin Glycation Index on the Diagnosis of Prediabetes and Diabetes
This analysis used D2d data (individuals with complete screening and baseline visit data) to calculate HGI, identify demographic and clinical variables associated with HGI, and...

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2018

D2d Participant Visits Completed
The last participant study visit was completed at the Northwestern site. This is a very exciting time for both participants and researchers alike! Since the...

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D2d Publication: Financial Management of large, multi-center trials
Randomized clinical trials that have public health implications but no or low potential for commercial gain are predominantly funded by governmental (e.g., National Institutes of...

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D2d Establishes a Participant Registry
A future long-term observational follow-up study (with no pills or visits) is being considered for the purpose of collecting simple health information to learn more...

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D2d Publication: Baseline characteristics of the D2d cohort
D2d is the largest clinical trial designed specifically to examine the causal relationship between vitamin D supplementation and the development of diabetes. D2d is also...

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2017

D2d Investigators’ Meeting
The annual meeting of the D2d research team is held in Washington D.C.. On Sunday evening, Principal Investigator Dr. Pittas presents the State of D2d, which...

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Interim analysis results are reviewed
The Data and Safety Monitoring Board (DSMB) reviews the results of the interim analysis. This is a critical juncture in the conduct of any clinical...

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D2d Publication: Assessment of the NDEP diabetes prevention toolkit
The National Diabetes Education Program created the Small Steps. Big Rewards. GAME PLAN. toolkit to deliver basic type 2 diabetes prevention information to individuals at risk....

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D2d enrolls last participant
A patient from the New York Lenox Hospital site is the 2,423rd and last participant enrolled in D2d. The participant completed the study. Congratulations to...

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2016

D2d meets enrollment goal
A participant from the Atlanta VA Medical Center site is the 2,382nd participant enrolled in D2d. The study’s recruitment goal is achieved. This is a...

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D2d Publication: Management of hemoglobin variants during hemoglobin A1c testing
When measuring HbA1c, many clinical laboratories do not report the presence of hemoglobin variants, whereas others report them only if they interfere with HbA1c measurement....

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D2d Investigators’ Meeting
The annual meeting of the D2d research team is held in Arlington, VA. On Sunday evening, principal investigator Dr. Pittas presents the State of D2d,...

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D2d enrolls 2,000th participant
A participant from the Pennington Biomedical Research Center site is the 2,000th participant enrolled in D2d. The participant completed the study....

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2015

D2d enrolls 1,500th participant
A participant from the Northwestern University site is the 1,500th participant enrolled in D2d. The participant completed the study....

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D2d Investigators’ Meeting
The annual meeting of the D2d research team is held in Arlington, VA. On Sunday evening, principal investigator Dr. Pittas presents the State of D2d,...

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D2d enrolls 1,000th participant
A participant from the MedStar Community Clinical Research Center D2d site is the 1,000th participant enrolled in D2d. The participant completed the study.    ...

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2014

DSMB is pleased with recruitment progress
The D2d Data and Safety Monitoring Board (DSMB) meets twice a year to review the study’s progress. At this meeting, the DSMB is impressed with...

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D2d Investigators’ Meeting
The annual meeting of the D2d research team is held in Crystal City, MD. On Sunday evening, principal investigator Dr. Pittas presents the State of...

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First D2d Publication: Rationale and Design of D2d
The D2d team publishes its first manuscript related to D2d: The rationale and Design of the Vitamin D and Type 2 Diabetes (D2d) Study: A...

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D2d enrolls 500th participant
A participant at the Atlanta VA Medical Center site is the 500th participant enrolled in D2d. The participant completed the study....

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2013

D2d enrolls 1st participant
A patient at the University of Kansas site is the 1st participant enrolled in D2d. The participant is still in D2d....

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Press release on D2d
Tufts Medical Center (where the D2d Coordinating Center is based) and NIDDK coordinate a press release to announce the official start of D2d activities....

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Participant recruitment begins
D2d begins screening people at high risk for diabetes to join D2d. Screening takes place in many medical centers throughout the United States. The first...

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U.S. government shutdown delays the start of recruitment
The U.S. federal government enters a shutdown because neither legislation appropriating funds for fiscal year 2014 nor a continuing resolution for the interim authorization of...

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D2d becomes the first NIDDK supported trial to use IRBShare
Obtaining IRB approval from each separate collaborating clinical site has long been considered a major reason for delaying the start of activities in multi-center trials....

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Investigators’ Kick-off meeting
The first meeting of the D2d Research Group is held in Bethesda, MD. Investigators and coordinators from all sites and all supporting units (e.g., central laboratory,...

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U01 grant to conduct D2d is formally awarded
Tufts Medical Center receives the U01 cooperative agreement grant to fund and conduct D2d. The grant is awarded by NIDDK and the NIH Office of...

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The D2d DSMB inaugural meeting takes place
The inaugural meeting of the D2d Data Safety Monitoring Board (DSMB) takes place in Bethesda, MD. The core D2d team – composed of Dr. Pittas...

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2012

U01 cooperative agreement grant application undergoes scientific review
The U01 grant application seeking funding for D2d undergoes a highly favorable scientific peer review by a NIH Special Emphasis Study Section, specifically convened to...

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U01 cooperative agreement grant is submitted
The D2d team submits a U01 grant application to NIH for funding to conduct D2d. Assembling a 1,140-page grant application was a Herculean effort by...

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Progress of U34 planning phase is reviewed favorably
An External Evaluation Committee convened by NIDDK reviews the progress of the U34 planning phase. The Committee concludes that the D2d team has made excellent...

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Association between higher blood level of vitamin D and lower risk of diabetes among adults with prediabetes is reported
This observational study was to assess the longitudinal association between vitamin D status – assessed by blood level of 25-hydroxyvitamin D – and risk of developing diabetes among...

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2011

The Origin of the D2d logo
The D2d logo was created in the summer of 2011. The three elements (D, 2, d) were chosen to represent the D2d study in the...

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CaDDM clinical trial results are published
Results of the Vitamin D and Calcium Homeostasis for Prevention of Type 2 Diabetes (CaDDM) study support a mechanistic link between vitamin D and diabetes...

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U34 planning grant is awarded
Dr. Pittas and colleagues are awarded a Multi-Center Clinical Study Implementation Planning Cooperating Agreement (U34) grant. The NIDDK-supported grant provides support to a core team...

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2010

U34 planning grant application undergoes scientific review
The U34 grant application undergoes a highly favorable scientific peer review by an NIH Special Emphasis Study Section, specifically convened to review the application. Over...

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Association between higher blood level of vitamin D and lower risk of diabetes among women is reported
An observational study in the Nurses’ Health Study – a longitudinal cohort of women – supports an association between higher blood level of vitamin D and...

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U34 planning grant application is submitted
Dr. Pittas and colleagues submit the Multi-Center Clinical Study Implementation Planning Cooperating Agreement (U34) grant application to NIH.  The goals of the U34 grant are...

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NIDDK allows submission of a U34 planning grant application to plan the D2d study
During the spring and early summer of 2010, the D2d concept goes through additional rounds of review within NIDDK. In July of 2010, Dr. Pittas...

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NIDDK Large Studies Committee reviews preliminary concept of D2d
In December of 2009, Dr. Pittas submits a pre-application to NIDDK proposing the study concept of D2d. The scientific justification of D2d and the preliminary...

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2008

Observational study to examine the association between vitamin D status and future diabetes risk in adults with prediabetes is funded
Dr. Pittas and colleagues receive funding by the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) and the Office of Dietary Supplements (ODS)...

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2007

Observational study to examine the association between vitamin D status and future diabetes risk in women is funded
Dr. Pittas and colleagues receive funding by the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) of the National Institutes of Health (NIH)...

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Effect of combined Calcium and Vitamin D supplementation in non-diabetic adults is published
In a post-hoc analysis using data from a completed trial, vitamin D and calcium supplementation given over 3 years improved insulin resistance and fasting blood...

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2006

The CaDDM clinical trial is funded
Based on strong preliminary data generated by Dr. Pittas and colleagues, the Vitamin D and Calcium Homeostasis for Prevention of Type 2 Diabetes (CaDDM) study...

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2002

Idea is conceived
The idea that vitamin D is linked to risk of developing type 2 diabetes is conceived by Dr. Pittas. In 2002, Dr. Pittas enrolled in...

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