Colonic diverticular disease (CDD) and colonic diverticular hemorrhage (CDH) are the most common disorders in hospital admissions and outpatient health clinic visits. However, risk factors of CDD and CDH are complicated and need to be discussed. Diabetes mellitus (DM) has been related with CDD and CDH, but the associations remain ambiguous. Therefore, we performed a literature search for studies involving the associations among DM, morbidity of CDD, and incidence of CDH. Relative risks or odds ratios with their corresponding 95% confidence intervals (CIs) were combined and weighted to produce summary effect size. Sensitivity analysis and subgroup analysis were further performed. We selected 17 studies that involved a total of 8212 patients with diabetes, 381,579 controls without diabetes. We found that patients with DM had approximately 1.201 times higher CDD morbidity in prospective studies (95% CI, 1.135-1.270) with no significant heterogeneity (Q = 0.42, P = 0.519, I = 0%). DM was associated with a 52.8% increase in risk of CDH (95% CI, 14%-104%); we did not find significant heterogeneity among these studies (Q = 12.94, P = 0.114, I = 38.2%). This meta-analysis confirms that DM is an important risk factor for morbidities of CDD and CDH.