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Effect of Vitamin D and Omega-3 Fatty Acid Supplementation on Kidney Function in Patients With Type 2 Diabetes: A Randomized Clinical Trial.

  • de Boer, Ian H1, 2, 3
  • Zelnick, Leila R1, 2
  • Ruzinski, John2
  • Friedenberg, Georgina4
  • Duszlak, Julie4
  • Bubes, Vadim Y4
  • Hoofnagle, Andrew N1, 5
  • Thadhani, Ravi6
  • Glynn, Robert J4, 7
  • Buring, Julie E4, 7
  • Sesso, Howard D4, 7
  • Manson, JoAnn E4, 7
  • 1 Division of Nephrology, Department of Medicine, University of Washington, Seattle.
  • 2 Kidney Research Institute, University of Washington, Seattle.
  • 3 Puget Sound VA Healthcare System, Seattle, Washington.
  • 4 Division of Preventive Medicine, Brigham and Women's Hospital, Boston, Massachusetts.
  • 5 Department of Laboratory Medicine, University of Washington, Seattle.
  • 6 Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, California.
  • 7 Harvard T. H. Chan School of Public Health, Boston, Massachusetts.
Published Article
American Medical Association
Publication Date
Nov 08, 2019
DOI: 10.1001/jama.2019.17380
PMID: 31703120


Chronic kidney disease (CKD) is a common complication of type 2 diabetes that can lead to end-stage kidney disease and is associated with high cardiovascular risk. Few treatments are available to prevent CKD in type 2 diabetes. To test whether supplementation with vitamin D3 or omega-3 fatty acids prevents development or progression of CKD in type 2 diabetes. Randomized clinical trial with a 2 × 2 factorial design conducted among 1312 adults with type 2 diabetes recruited between November 2011 and March 2014 from all 50 US states as an ancillary study to the Vitamin D and Omega-3 Trial (VITAL), coordinated by a single center in Massachusetts. Follow-up was completed in December 2017. Participants were randomized to receive vitamin D3 (2000 IU/d) and omega-3 fatty acids (eicosapentaenoic acid and docosahexaenoic acid; 1 g/d) (n = 370), vitamin D3 and placebo (n = 333), placebo and omega-3 fatty acids (n = 289), or 2 placebos (n = 320) for 5 years. The primary outcome was change in glomerular filtration rate estimated from serum creatinine and cystatin C (eGFR) from baseline to year 5. Among 1312 participants randomized (mean age, 67.6 years; 46% women; 31% of racial or ethnic minority), 934 (71%) completed the study. Baseline mean eGFR was 85.8 (SD, 22.1) mL/min/1.73 m2. Mean change in eGFR from baseline to year 5 was -12.3 (95% CI, -13.4 to -11.2) mL/min/1.73 m2 with vitamin D3 vs -13.1 (95% CI, -14.2 to -11.9) mL/min/1.73 m2 with placebo (difference, 0.9 [95% CI, -0.7 to 2.5] mL/min/1.73 m2). Mean change in eGFR was -12.2 (95% CI, -13.3 to -11.1) mL/min/1.73 m2 with omega-3 fatty acids vs -13.1 (95% CI, -14.2 to -12.0) mL/min/1.73 m2 with placebo (difference, 0.9 [95% CI, -0.7 to 2.6] mL/min/1.73 m2). There was no significant interaction between the 2 interventions. Kidney stones occurred among 58 participants (n = 32 receiving vitamin D3 and n = 26 receiving placebo) and gastrointestinal bleeding among 45 (n = 28 receiving omega-3 fatty acids and n = 17 receiving placebo). Among adults with type 2 diabetes, supplementation with vitamin D3 or omega-3 fatty acids, compared with placebo, resulted in no significant difference in change in eGFR at 5 years. The findings do not support the use of vitamin D or omega-3 fatty acid supplementation for preserving kidney function in patients with type 2 diabetes. Identifier: NCT01684722.

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