No effect of selenium supplementation on serum glucose levels in men with prostate cancer

Background: Literature indicates a relationship between selenium supplementation and risk of diabetes. However, because these data are inconclusive, we investigated the effect of selenium supplementation on serum glucose levels in men with prostate cancer enrolled in a clinical trial testing of the effect of selenium on prostate cancer progression. Methods: Subjects were randomized to receive placebo (n = 46), selenium 200 μg/day (n = 47), and selenium 800 μg/day (n = 47). Serum glucose levels were obtained every 6 months for up to 5 years. Longitudinal analysis was carried out to assess whether rate of change of serum glucose levels was significantly different in the selenium-supplemented groups as compared with placebo. Sensitivity analyses were performed to assess the robustness of findings. Results: Changes in serum glucose levels during the course of the trial were not statistically significantly different as compared with placebo for the selenium 200 μg/day (P = .56) or selenium 800 μg/day (P = .91) treatment groups. Conclusion: These results do not support a relationship between selenium supplementation and changes in serum glucose levels. Recommendations about selenium supplementation and risk of diabetes will require more definitive studies.