title: Association between serum selenium level and type 2 diabetes mellitus: a non-linear dose-response meta-analysis of observational studies.
abstract: The association between serum selenium levels and type 2 diabetes mellitus (T2DM) is controversial. We performed a systematic review and non-linear dose-response meta-analysis of observational studies to investigate the association in the present study.
  
  
  
  A comprehensive literature search was conducted using MEDLINE and EMBASE databases. A pooled odds ratio (OR) and related 95 % confidence interval (95 % CI) for T2DM between the highest and lowest serum selenium categories, and a non-linear dose-response relationship between selenium and T2DM were estimated.
  
  
  
  A total of five studies (of 13,460 participants) were identified as meeting the inclusion criteria. The pooled OR indicated that there was a significantly higher prevalence of T2DM in the highest category of blood selenium compared with the lowest (OR = 1.63, 95 % CI: 1.04-2.56, P = 0.033). Moreover, a significant non-linear dose-response relationship was observed between serum selenium levels and T2DM (P < 0.001). Serum selenium levels were positively associated with T2DM in populations with relatively low serum selenium levels (<97.5 μg/l) and those with high serum selenium levels (>132.5 μg/l).
  
  
  
  The positive association between serum selenium levels and T2DM existed in populations with relatively low levels and high levels of serum selenium, indicating a likely U-shaped non-linear dose-response relationship between serum selenium and T2DM.
authors.affiliation: Department of Epidemiology and Health Statistics, Xiangya School of Public Health, Central South University, Changsha, 410008, Hunan Province, China.
authors.forename: Xin-Liang
authors.initials: XL
authors.lastname: Wang
authors.affiliation: Department of Epidemiology and Health Statistics, Xiangya School of Public Health, Central South University, Changsha, 410008, Hunan Province, China. 1064960669@qq.com.
authors.forename: Tu-Bao
authors.initials: TB
authors.lastname: Yang
authors.affiliation: Department of Epidemiology and Health Statistics, Xiangya School of Public Health, Central South University, Changsha, 410008, Hunan Province, China. weijie60112@163.com.|Health Management Center, Xiangya Hospital, Central South University, Changsha, 410008, Hunan Province, China. weijie60112@163.com.
authors.forename: Jie
authors.initials: J
authors.lastname: Wei
authors.affiliation: Department of Orthopaedics, Xiangya Hospital, Central South University, Changsha, 410008, Hunan Province, China.
authors.forename: Guang-Hua
authors.initials: GH
authors.lastname: Lei
authors.affiliation: Department of Orthopaedics, Xiangya Hospital, Central South University, Changsha, 410008, Hunan Province, China.
authors.forename: Chao
authors.initials: C
authors.lastname: Zeng
mesh_terms: D000368:Aged; D003924:Diabetes Mellitus, Type 2 / Q000097:blood* / Q000453:epidemiology; D005260:Female; D006801:Humans; D016239:MEDLINE; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D012307:Risk Factors; D012643:Selenium / Q000097:blood*
chemical_list: D012643:Selenium
keywords: Non-linear dose–response meta-analysis; Observational studies; Selenium; Type 2 diabetes mellitus