Alcohol abuse and nonalcoholic fatty liver disease (NAFLD) are common causes of liver disease. Diabetes mellitus (DM) is a common comorbidity among NAFLD patients. We performed this study with the specific aim to examine the impact of DM on progression of alcoholic liver disease (ALD) liver and NAFLD. Medical charts of 480 patients with ALD or NAFLD (2004-2011) managed at a tertiary center were retrospectively reviewed. NAFLD was diagnosed based on exclusion of other causes of liver disease and alcohol use of <10 g/d. ALD was diagnosed based on alcohol use of >40 g/d in women or >60 g/d in men for >5 years. Of 480 patients (307 NAFLD), 200 diabetics differed from nondiabetics for: age (52±11 vs. 49±11 years; p=0.004); male gender (48% vs. 57%; p=0.03); metabolic syndrome (49% vs. 30%; p=0.0002); NAFLD (80% vs. 56%; p<0.0001); cirrhosis (70% vs. 59%; p=0.005); and hepatocellular carcinoma (HCC; 8% vs. 3%; p=0.009). Over a 3 year median follow-up period, diabetics relative to nondiabetics had a higher probability to develop cirrhosis (60% vs. 41%; p=0.022) and HCC (27% vs. 10%; p=0.045). There was a trend for increased development of hepatic encephalopathy in diabetics compared to nondiabetics (55% vs. 39%; p=0.053), and there was no difference between the two groups in survival or other liver disease complications. DM increased risk for cirrhosis and HCC among patients with ALD and NAFLD. Prospective studies with longer follow-up periods are needed to examine the impact of DM on survival and the role of aggressive HCC screening in diabetic cirrhotics.