The Effectiveness of Lubiprostone in Constipated Diabetics

The investigators will recruit a total of 136 diabetic men and women with constipation into this study from both The Emory Clinic and The Atlanta Veteran's Administration Hospital. The investigators will track spontaneous bowel movements defined as a bowel movement in 24 hours after initiation of study drug (SBMs) in all patients two weeks before treatment with lubiprostone as well as measure baseline colonic transit using the Smartpill pH capsule. Colon transit reflects that rate of colonic peristalsis and movement of stool through the large bowel. Patients will receive either lubiprostone 24 micrograms (mcg) orally twice a day for 8 weeks or placebo. Primary and secondary endpoints will be the number of SBMs/week and colonic transit time as measured by the Smartpill capsule, respectively. The number of SBMs/week will be evaluated at 0, 2, 4 and 8 weeks after initiation of therapy. The investigators will over-sample African American patients to achieve approximately 50% enrollment of this group. In a subanalysis, the investigators will assess response to treatment between the general population and African Americans. We hypothesize that lubiprostone will significantly increase the number of SBMs as well as decrease colonic transit time and improve quality of life in constipated diabetic patients compared with placebo.