Serum selenium in relation to measures of glucose metabolism and incidence of Type 2 diabetes in an older Swedish population

Aims The relation between selenium status and risk of Type 2 diabetes is controversial. We aimed to evaluate associations of serum selenium, a marker of dietary selenium, with measures of glucose metabolism and risk of diabetes. Methods We used data from a population‐based, longitudinal cohort of 1925 Swedish men who were 50 years old and did not have diabetes at baseline in the 1970s. At baseline, an intravenous glucose tolerance test was performed and, at a follow‐up examination after 20 years, an oral glucose tolerance test and a hyperinsulinaemic euglycaemic clamp for the assessment of insulin sensitivity were conducted. Results At baseline, the mean (standard deviation) selenium concentration was 75.6 (14.3) μg/l. During 20 years of follow‐up, 88 incident cases of diabetes occurred in 1024 participants with follow‐up data. Baseline serum selenium levels were not associated with risk of diabetes (odds ratio 1.06; 95% CI 0.83–1.38). Higher selenium levels were associated with lower early insulin response (standardized β –0.08; 95% CI –0.14 to –0.03) at baseline after adjusting for potential confounders, but not with any other measures of β‐cell function or insulin sensitivity at baseline or follow‐up. The association with early insulin response was non‐significant after taking multiple testing into account. Conclusions Our results do not support a role of dietary selenium in the development of disturbances in glucose metabolism or diabetes in older individuals. What's new? The relation between selenium intake and risk of Type 2 diabetes is controversial. Our results from a longitudinal cohort study indicate no substantial association of selenium status with incidence of diabetes and various physiological measures of glucose and insulin metabolism, including an euglycaemic clamp test. Our study adds to the currently lacking evidence from prospective cohort studies and does not support selenium supplementation as a broad approach for the prevention of diabetes.