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Ann Intern Med. 2007 Aug 21;147(4):217-23. Epub 2007 Jul 9.

Effects of long-term selenium supplementation on the incidence of type 2 diabetes: a randomized trial.

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State University of New York at Buffalo and Cancer Prevention and Population Sciences, Roswell Park Cancer Institute, Buffalo, New York, USA.



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


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


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


Areas of low selenium consumption of the eastern United States.


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


Oral administration of selenium, 200 microg/d, or placebo.


Incidence of type 2 diabetes.


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]).


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.


Selenium supplementation does not seem to prevent type 2 diabetes, and it may increase risk for the disease. Click here for related information on selenium.

[Indexed for MEDLINE]

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