Diabetes mellitus and risk of pancreatic cancer: A meta-analysis of cohort studies

Background: Diabetes mellitus (DM) is widely considered to be associated with risk of pancreatic cancer (PaC), however, whether DM is a cause or a consequence of PaC is still controversial. We examined this association by conducting a detailed meta-analysis of cohort studies. Methods: Studies were identified by searching Medline and Embase through November 30, 2010. Summary relative risks (RRs) with their corresponding 95% confidence intervals (CIs) were calculated using a random-effects model. Results: A total of thirty-five cohort studies were included in this meta-analysis. DM was associated with an increased risk of PaC (the summary RRs = 1.94; 95% CI, 1.66-2.27), with significant evidence of heterogeneity among these studies (p < 0.001, I-2 = 93.6%). Subgroup analyses revealed that the increased risk of PaC was independent of geographic locations, sex, study design, alcohol consumption, body mass index (BMI) and smoking status. In addition, the relative risk of PaC was correlated negatively with the duration of DM, with the highest risk of PaC found among patients diagnosed within less than 1 year. There was no significant publication bias (p = 0.136 for Egger's regression asymmetry test). Conclusions: Findings from this meta-analysis strongly support that diabetes is associated with an increased risk of PaC in both males and females and that DM is both an early manifestation and an etiologic factor of pancreatic cancer. (C) 2011 Elsevier Ltd. All rights reserved.