title: Diabetes mellitus and risk of gastric cancer:  a systematic review and meta-analysis of observational studies.
abstract: OBJECTIVE
  Increasing evidence suggests that a history of diabetes may be involved in the development of various sites of cancer. However, the association of diabetes and risk of gastric cancer (GC) remains unclear.
  
  
  METHODS
  We identified studies by a literature search of MEDLINE (from 1 January 1966), Web of Science (from 1 January 1994), and EMBASE (from 1 January 1974 through 31 May 2011), and by searching the reference lists of pertinent articles. All data were extracted independently by two investigators using a standardized data abstraction tool. Summary relative risks (SRRs) with 95% confidence intervals (CIs) were calculated with a random-effects model. Between-study heterogeneity was assessed using the Cochran's Q and I statistics.
  
  
  RESULTS
  A total of 21 studies (four case-control studies, 17 cohort studies) were included in this meta-analysis. Analysis of these 21 studies found that compared with nondiabetic individuals, diabetic individuals had a similar risk of GC (SRRs, 1.09; 95% CI: 0.98-1.22). There was strong evidence of heterogeneity among these studies (P<0.001, I²=81.2%). A subgrouped analysis found that diabetic women had 18% increased risk of GC (SRRs, 1.18; 95% CI: 1.01-1.39), whereas it was not the case with diabetic men. No significant public bias was found in this study.
  
  
  CONCLUSIONS
  These findings of this systematic review indicate that compared with nondiabetic individuals, diabetic women have an 18% increased risk of GC development. However, diabetic men have a similar risk of GC.
authors.affiliation: Department of Gastroenterology, The First People's Hospital of Nantong, Jiangsu, China.
authors.forename: Zhenming
authors.initials: Z
authors.lastname: Ge
authors.forename: Qiwen
authors.initials: Q
authors.lastname: Ben
authors.forename: Junbo
authors.initials: J
authors.lastname: Qian
authors.forename: Yamin
authors.initials: Y
authors.lastname: Wang
authors.forename: Yuming
authors.initials: Y
authors.lastname: Li
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D048909:Diabetes Complications / Q000453:epidemiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017594:Publication Bias; D018570:Risk Assessment / Q000379:methods; D012737:Sex Factors; D013274:Stomach Neoplasms / Q000453:epidemiology*