High serum selenium levels are associated with increased risk for diabetes mellitus independent of central obesity and insulin resistance

Objective: Selenium is an essential micronutrient for human health. Although many observational and interventional studies have examined the associations between selenium and diabetes mellitus, the findings were inconclusive. This study aimed to investigate the relationship between serum selenium levels and prevalence of diabetes, and correlated the relationship to insulin resistance and central obesity.

Research design and methods: This was a hospital-based case-control study of 847 adults aged more than 40 years (diabetes: non-diabetes =1:2) in Northern Taiwan. Serum selenium was measured by an inductively coupled plasma-mass spectrometer. The association between serum selenium and diabetes was examined using multivariate logistic regression analyses.

Results: After adjusting for age, gender, current smoking, current drinking, and physical activity, the ORs (95% CI, p value) of having diabetes in the second (Q2), third (Q3), and fourth (Q4) selenium quartile groups were 1.24 (95% CI 0.78 to 1.98, p>0.05), 1.90 (95% CI 1.22 to 2.97, p<0.05), and 5.11 (95% CI 3.27 to 8.00, p<0.001), respectively, compared with the first (Q1) quartile group. Further adjustments for waist circumference and homeostatic model assessment-insulin resistance (HOMA-IR) largely removed the association of serum selenium levels with diabetes but not in the highest quartile (compared with Q1, Q3: 1.57, 95% CI 0.91 to 2.70, Q4: 3.79, 95% CI 2.17 to 6.32).

Conclusions: We found that serum selenium levels were positively associated with prevalence of diabetes. This is the first human study to link insulin resistance and central obesity to the association between selenium and diabetes. Furthermore, the association between selenium and diabetes was independent of insulin resistance and central obesity at high serum selenium levels. The mechanism behind warrants further confirmation.