DM (diabetes mellitus) is present in 20–40% of patients with liver cirrhosis, but its prognostic impact is unclear. Therefore, in the present study, we investigated whether the presence of DM in patients with cirrhosis was associated with increased mortality, and/or with increased incidence of SBP (spontaneous bacterial peritonitis). We reviewed medical and laboratory data of 230 patients with cirrhosis from the period 2001–2011, for whom data were complete in n =226. Follow-up for the outcomes mortality and SBP was performed until May 2012, with only 13 patients lost to follow-up. DM was present at baseline in 78 patients (35%). Median follow-up was 6.2 (interquartile range, 3.1–9.3) years, during which 118 patients died [47 out of 78 with DM (60%), and 71 out of 148 without DM (48%)]. The presence of DM at baseline was not associated with increased mortality after adjustment for age {HR (hazard ratio), 1.00 [95% CI (confidence interval), 0.67–1.50]}. Further adjustment for sex, aetiology of cirrhosis, platelet count and the Child–Pugh or MELD (model for end-stage liver disease) score did not change this finding. During follow-up, 37 patients developed incident SBP (19 with DM and 18 without DM). DM at baseline was associated with incident SBP, even after adjustment for age, sex, aetiology, platelet count and the Child–Pugh [HR, 2.39 (95% CI, 1.10–5.18)] or MELD score [HR, 2.50 (95% CI, 1.16–5.40)]. In conclusion, the presence of DM at baseline in patients with cirrhosis was associated with an increased risk of SBP, which may represent an increased susceptibility to infections. On the other hand, DM was not clearly associated with increased mortality in these patients.