Diabetes mellitus and the incidence of colorectal cancer: an updated systematic review and meta-analysis

Dig Dis Sci. 2012 Jun;57(6):1576-85. doi: 10.1007/s10620-012-2055-1. Epub 2012 Feb 17.


Aim: The purpose of this study was to determine whether diabetes mellitus is associated with an increased risk of colorectal cancer.

Methods: Relevant studies were identified in MEDLINE and EMBASE (up until November 1st, 2011). Inclusion criteria were original, peer-reviewed publications, with case-control and cohort studies (for studies on diabetes mellitus and colorectal cancer). Summary relative risks with 95% confidence intervals were calculated with a random-effects model.

Results: Twenty-four studies including eight case-control and 16 cohort studies, with a total of 3,659,341 participants, were included in this updated systematic review and meta-analysis, and all involved diabetes mellitus and colorectal cancer risk. Meta-analysis of the 24 included studies indicated that diabetes was associated with an increased risk of colorectal cancer, compared with no diabetes (summary RR of colorectal cancer incidence = 1.26, 95% CI = 1.20-1.31), without heterogeneity between studies (P(heterogeneity) = 0.296). Sub-group analyses found that these results were consistent between case-control and cohort studies and among studies conducted in different areas. The association between diabetes and colorectal cancer incidence did not differ significantly by sex and sub-sites. Insulin therapy was also positively associated with risk of colorectal cancer (summary RR = 1.61, 95% CI 1.18-1.35), with evidence of heterogeneity between studies (P(heterogeneity) = 0.014).

Conclusions: Our findings further support a relationship between diabetes and increased risk of colon and rectal cancer in both women and men, and insulin therapy for diabetes may increase this risk.

Publication types

  • Comparative Study
  • Meta-Analysis
  • Research Support, Non-U.S. Gov't
  • Review
  • Systematic Review

MeSH terms

  • Age Distribution
  • Aged
  • Aged, 80 and over
  • Case-Control Studies
  • China / epidemiology
  • Cohort Studies
  • Colorectal Neoplasms / diagnosis
  • Colorectal Neoplasms / epidemiology*
  • Colorectal Neoplasms / therapy
  • Comorbidity
  • Diabetes Mellitus, Type 1 / diagnosis
  • Diabetes Mellitus, Type 1 / epidemiology*
  • Diabetes Mellitus, Type 1 / therapy
  • Diabetes Mellitus, Type 2 / diagnosis
  • Diabetes Mellitus, Type 2 / epidemiology*
  • Diabetes Mellitus, Type 2 / therapy
  • Female
  • Humans
  • Incidence
  • Male
  • Middle Aged
  • Prognosis
  • Sex Distribution
  • Survival Analysis