African Americans have the highest rate of DM compared with other ethnic groups in the Unites States. Furthermore, constipation is more prevalent in African Americans compared with other minority groups. However, there is little data evaluating the prevalence of constipation and the response to treatment in African Americans. Therefore, more information regarding the severity of symptoms, differences in bowel patterns, colonic transit, and response to therapy is important to improving the management of constipation in this group. Hence, in a subanalysis, we will study whether the responsiveness of African American patients to lubiprostone differs from that of the general population.