Diabetes mellitus is a disorder of glucose metabolism that affects 12 million people in the United States. 48 Diabetes primarily affects the liver and biliary system through its metabolic effects. Patients with either type I or type II diabetes of sufficient duration, including patients with secondary etiologies of diabetes such as chronic pancreatitis and hemochromatosis are susceptible to diabetic complications. 60 and 66 This article reviews the clinical features, diagnosis, and treatment of the hepatic and biliary complications of diabetes, as well as the glucose intolerance seen in liver disease.