Diabetes mellitus and risk of breast cancer: a meta-analysis

Int J Cancer. 2007 Aug 15;121(4):856-62. doi: 10.1002/ijc.22717.


Diabetes mellitus has been associated with an increased risk of several types of cancers, but its relationship with breast cancer remains unclear. We conducted a meta-analysis of case-control and cohort studies to assess the evidence regarding the association between diabetes and risk of breast cancer. Studies were identified by searching MEDLINE (1966-February 2007) and the references of retrieved articles. We identified 20 studies (5 case-control and 15 cohort studies) that reported relative risk (RR) estimates (odds ratio, rate ratio/hazard ratio, or standardized incidence ratio) with 95% confidence intervals (CIs) for the relation between diabetes (largely Type II diabetes) and breast cancer incidence. Summary RRs were calculated using a random-effects model. Analysis of all 20 studies showed that women with (versus without) diabetes had a statistically significant 20% increased risk of breast cancer (RR, 1.20; 95% CI, 1.12-1.28). The summary estimates were similar for case-control studies (RR, 1.18; 95% CI, 1.05-1.32) and cohort studies (RR, 1.20; 95% CI, 1.11-1.30). Meta-analysis of 5 cohort studies on diabetes and mortality from breast cancer yielded a summary RR of 1.24 (95% CI, 0.95-1.62) for women with (versus without) diabetes. Findings from this meta-analysis indicate that diabetes is associated with an increased risk of breast cancer.

Publication types

  • Meta-Analysis
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Asia
  • Body Mass Index
  • Breast Neoplasms / epidemiology*
  • Breast Neoplasms / mortality
  • Case-Control Studies
  • Cohort Studies
  • Diabetes Mellitus / epidemiology*
  • Europe
  • Female
  • Humans
  • Male
  • Menopause
  • Middle Aged
  • North America
  • Risk Factors