At the baseline visit, subjects will sign a consent form after all questions they have are answered. An inpatient appointment will be made at the General Clinical Research Center (GCRC). Subjects will be given instructions to fill out a 7-day food diary the week prior to their inpatient appointment. In this diary, subjects will be asked to record the types and amounts of food they ingest over a 7-day period. This will allow researchers to review subjects' food intake prior to sugar permeability testing. Although each subject serves as his/her own control, this information may be useful upon review of variations in permeability between subjects.