Effect of diabetes mellitus on survival in patients with gallbladder Cancer: a systematic review and meta-analysis

Background Increasing evidences indicated that diabetes might increase the incidence of gallbladder cancer. However, no sufficient data has ever clarified the impact of diabetes on the survival of patients with gallbladder cancer. Methods We comprehensively searched PubMed, Embase, and the Cochrane Library databases through July 2019 in order to find sufficient eligible researches. The pooled hazard risks (HRs) and relative risks (RRs) with 95% confidence intervals (CIs) were calculated with either fix-effects or random-effects model. Due to the low gallbladder cancer mortality in general population, the RRs and standard mortality ratios (SMRs) were considered the similar estimates of the HRs. Results Ten eligible studies were included in this meta-analysis. Analysis of eight cohorts found that diabetes was closely associated with the mortality of gallbladder cancer (HR = 1.10; 95% CI: 1.06-1.14;P < 0.00001). However, the mortality in male diabetes patients was not higher than female patients (RR = 1.08, 95%CI = 0.57-2.04,P = 0.80). Conclusions These findings indicated that diabetes patients had a higher mortality of gallbladder cancer compared with non-diabetes.