This review briefly outlines the gastrointestinal manifestations of diabetes mellitus. Usually, gastrointestinal abnormalities are asymptomatic. Severe gastrointestinal dysfunction may be quite debilitating, however. Gastrointestinal symptoms that are a consequence of diabetes may be confused with other primary gastrointestinal disorders. We attempt to provide a clinical approach to differentiating the basis of symptoms and outline the therapeutic plan that we generally employ. Much additional research is necessary to clarify our understanding of the pathophysiology of the gastrointestinal complications of diabetes and to develop improved therapeutic strategies.