Effects of Long-Term Selenium Supplementation on the Incidence of Type 2 Diabetes

A Randomized Trial

  1. Saverio Stranges, MD, PhD;
  2. James R. Marshall, PhD;
  3. Raj Natarajan, MS;
  4. Richard P. Donahue, PhD;
  5. Maurizio Trevisan, MD;
  6. Gerald F. Combs, PhD;
  7. Francesco P. Cappuccio, MD;
  8. Antonio Ceriello, MD; and
  9. Mary E. Reid, PhD
  1. From the State University of New York at Buffalo and Cancer Prevention and Population Sciences, Roswell Park Cancer Institute, Buffalo, New York; Clinical Sciences Research Institute, Warwick Medical School, Coventry, United Kingdom; and U.S. Department of Agriculture Human Nutrition Research Center, Grand Forks, North Dakota.

    Abstract

    Background: Findings from animal models suggest that selenium supplementation improves glucose metabolism.

    Objective: To examine the effect of long-term selenium supplementation on the incidence of type 2 diabetes.

    Design: Secondary analysis of a randomized, double-blind, placebo-controlled trial.

    Setting: Areas of low selenium consumption of the eastern United States.

    Patients: 1202 persons seen in dermatology clinics who did not have type 2 diabetes at baseline.

    Intervention: Oral administration of selenium, 200 μg/d, or placebo.

    Measurements: Incidence of type 2 diabetes.

    Results: During an average follow-up of 7.7 years (SD, 2.7), type 2 diabetes developed in 58 selenium recipients and 39 placebo recipients (incidence, 12.6 cases per 1000 person-years vs. 8.4 cases per 1000 person-years, respectively; hazard ratio, 1.55 [95% CI, 1.03 to 2.33]). The lack of benefit of selenium supplementation on the incidence of type 2 diabetes persisted in analyses stratified by age, sex, body mass index, and smoking status. An exposure–response gradient was found across tertiles of baseline plasma selenium level, with a statistically significantly increased risk for type 2 diabetes in the highest tertile of baseline plasma selenium level (hazard ratio, 2.70 [CI, 1.30 to 5.61]).

    Limitations: Diabetes was a secondary outcome in the parent trial. Diagnoses of diabetes were self-reported but were validated in most participants. The sample was mostly older and white.

    Conclusions: Selenium supplementation does not seem to prevent type 2 diabetes, and it may increase risk for the disease.

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    Article and Author Information

    • Potential Financial Conflicts of Interest: None disclosed.

    • Requests for Single Reprints: Saverio Stranges, MD, PhD, Clinical Sciences Research Institute, Warwick Medical School, University Hospital Coventry and Warwickshire, Clifford Bridge Road, Coventry CV2 2DX, United Kingdom; e-mail, s.stranges{at}warwick.ac.uk.

    • Current Author Addresses: Drs. Stranges, Cappuccio, and Ceriello: Clinical Sciences Research Institute, Warwick Medical School, University Hospital Coventry and Warwickshire, Clifford Bridge Road, Coventry CV2 2DX, United Kingdom.

    • Drs. Marshall and Reid and Mr. Natarajan: Roswell Park Cancer Institute, Carlton House Building, Elm and Carlton Streets, Buffalo, NY 14263.

    • Drs. Donahue and Trevisan: Department of Social and Preventive Medicine, State University of New York at Buffalo, South Campus, 3435 Main Street, Farber Hall, Buffalo, NY 14214.

    • Dr. Combs: Human Nutrition Research Center, U.S. Department of Agriculture, 2420 Second Avenue North, Stop 9034, Grand Forks, ND 58202.

    • Author Contributions: Analysis and interpretation of the data: S. Stranges, R. Natarajan, R.P. Donahue, M. Trevisan, G.F. Combs, F.P. Cappuccio.

    • Drafting of the article: S. Stranges, R.P. Donahue, M. Trevisan.

    • Critical revision of the article for important intellectual content: S. Stranges, R.P. Donahue, M. Trevisan, G.F. Combs, F.P. Cappuccio.

    • Final approval of the article: S. Stranges, M. Trevisan, F.P. Cappuccio.

    • Statistical expertise: R. Natarajan, M. Trevisan.

    • Administrative, technical, or logistic support: G.F. Combs, F.P. Cappuccio.

    • Collection and assembly of data: G.F. Combs.

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