Objective: Describe baseline characteristics of the NIH/ADA-supported D2d study, the first diabetes prevention trial in the U.S. to apply current ADA diagnostic glycemia criteria.

Research Design and Methods: Multicenter (22 sites), randomized, double-blind, placebo-controlled, primary prevention trial testing efficacy of oral daily 4000 IU cholecalciferol (D3) compared to placebo on incident diabetes in adults at high risk. Eligible participants met at least 2-of-3 2010 ADA glycemic criteria for prediabetes: fasting plasma glucose (FPG) 100-125 mg/dL, 2-hour glucose post-75g oral glucose load (2hPG) 140-199 mg/dL, and/or hemoglobin A1c (HbA1c) 5.7-6.4%.

Results: 2423 participants (45% women, 33% non-white) were randomized. Mean (±SD) age was 59 (±9.9) years, and BMI was 32 (±4.5) kg/m2. Thirty-five percent met 3 prediabetes criteria, 49% met FPG/HbA1c criteria only, 9.5% met 2hPG/FPG criteria only, and 6.3% met 2hPG/HbA1c criteria only. Black participants had higher HbA1c and lower FPG concentration than white, Asian, and other races (P<0.01); 2hPG concentration did not differ by race (Table). The D2d cohort has lower 2hPG but similar HbA1c and FPG concentrations than previous prediabetes cohorts.

Conclusions: D2d will establish the efficacy and safety of vitamin D supplementation for diabetes prevention and inform on the natural history of prediabetes per contemporary ADA criteria.


E. LeBlanc: None. R.E. Pratley: Other Relationship; Self; AstraZeneca, Boehringer Ingelheim Pharmaceuticals, Inc., Eisai Inc., GlaxoSmithKline plc., Janssen Pharmaceuticals, Inc., Lexicon Pharmaceuticals, Inc., Ligand Pharmaceuticals, Inc., Eli Lilly and Company, Merck & Co., Inc., Novo Nordisk Inc., Pfizer Inc., Sanofi-Aventis, Takeda Development Center Americas, Inc.. B. Dawson-Hughes: None. M.A. Staten: None. P.R. Sheehan: None. M.R. Lewis: None. A.L. Peters: Advisory Panel; Self; Abbott, Bigfoot Biomedical. Research Support; Self; Dexcom, Inc.. Advisory Panel; Self; Eli Lilly and Company, Insulin Algorithms, JDRF, Lexicon Pharmaceuticals, Inc., Livongo Health. Research Support; Self; MannKind Corporation. Other Relationship; Self; Medscape. Advisory Panel; Self; Merck & Co., Inc.. Research Support; Self; National Institute of Diabetes and Digestive and Kidney Diseases. Speaker's Bureau; Self; Novo Nordisk Inc.. Advisory Panel; Self; Novo Nordisk Inc., Omada Health, Inc., Optum Rx, Inc., Sanofi. Research Support; Self; T1D Exchange. Advisory Panel; Self; The Endocrine Society. Research Support; Self; The Leona M. and Harry B. Helmsley Charitable Trust. Advisory Panel; Spouse/Partner; Johnson & Johnson Diabetes Institute, LLC.. S.H. Kim: None. R. Chatterjee: None. V. Aroda: Consultant; Self; Novo Nordisk Inc.. Research Support; Self; Novo Nordisk Inc., AstraZeneca, Calibra Medical, Eisai Inc., Sanofi. Consultant; Self; Sanofi. Research Support; Self; Theracos, Inc.. Employee; Spouse/Partner; Merck & Co., Inc.. Other Relationship; Self; American Diabetes Association. Consultant; Self; ADOCIA. C. Chadha: None. A. Pittas: None.

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