**5. Conclusions**

This meta-analysis demonstrated that selenium supplementation may reduce the levels of serum insulin and HOMA-IR, and increase serum HDL-C levels, suggesting that selenium supplementation may be beneficial for reducing insulin resistance in patients with CMDs. This finding may provide support to prospective studies looking into selenium supplementation to manage cardiometabolic risk factors. However, in the case of selenium excess, the efficacy of selenium supplementation on glucolipid metabolism needs further evaluation.

**Supplementary Materials:** The following supporting information can be downloaded at: https: //www.mdpi.com/article/10.3390/nu14224933/s1, Table S1. Search strategy for each electronic database; Figure S1. Sensitivity analysis of insulin levels; Figure S2. Sensitivity analysis of HOMA-IR; Figure S3. Forest plot of FPG; Figure S4. Sensitivity analysis of FPG; Figure S5. Forest plot of HDL-C; Figure S6. Sensitivity analysis of HDL-C; Figure S7. Forest plot of HDL-C after excluding Ghazi 2021 [42].

**Author Contributions:** Conceptualization and design, A.W., R.B. and Z.G.; software, J.O., Y.C. and Y.S.; validation, A.W. and R.B.; writing—original draft preparation, J.O., Y.C.; writing—review and editing, A.W. and R.B. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by the National Natural Science Foundation of China (No. 82174216 AND No. 82004194), the Fundamental Research Funds for the Central public welfare research institutes (No. ZZ13-YQ-005, No. ZZ13-YQ-005-C1, No. ZZ13-YQ-014-C1 and No. ZZ13- YQ-014) and Scientific Fund of National Clinical Research Center for Chinese Medicine Cardiology (No. CMC2022009).

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Not applicable.

**Conflicts of Interest:** The authors declare no conflict of interest.
