Serum selenium level and gestational diabetes mellitus: a systematic review and meta-analysis

BACKGROUND: The association between serum selenium level and gestational diabetes mellitus (GDM) is controversial. The aim of our study was to systematically review available literature linking selenium to GDM for a comprehensive understanding of the relationship between serum selenium level and GDM in human. METHODS: PubMed, The Cochrane Library and Medline were searched for studies published up to August 2016. Manual searches of references of the relevant original studies were carried out. Pooled estimates were measured using the fixed or random effect model. Overall effect was reported in a standard mean difference (SMD). All data were analyzed with Review Manager 5.3 and Stata 12.0. RESULTS: Of 44 references reviewed, seven studies involving 569 patients met our inclusion criteria and contributed to meta-analysis. All the studies were used to evaluate the relationship between serum selenium level and GDM. Selenium level was significantly lower in women with GDM than those without GDM (SMD = −1.17; 95 % CI: −1.98 to −0.35, P = 0.005). Subgroup analysis showed that such trend was consistent within the non-Caucasian population (Asia: SMD = −2.82; 95 % CI: −5.21 to −0.43, P = 0.02; Africa: SMD = −0.56; 95 % CI: −1.07 to −0.05, P = 0.03) and in the third trimester (SMD = −1.78; 95 % CI: −3.04 to −0.52, P = 0.006), but not within the Caucasian population (Europe: SMD = −0.6; 95 % CI: −1.98 to 0.78, P = 0.39) or in the second trimester (SMD = −0.68; 95 % CI: −1.6 to 0.25, P = 0.15). CONCLUSIONS: The available evidences suggested that serum selenium level was lower in women with GDM than those with normal glucose tolerance, especially within the non-Caucasian population and in the third trimester. However, well-designed prospective studies are needed to understand dynamic associations between selenium status and GDM risk.