1. Division of Gastroenterology and Hepatology , Department of Internal Medicine, , Iowa City, IA 52242 , United States
2. University of Iowa Hospitals and Clinics , Department of Internal Medicine, , Iowa City, IA 52242 , United States
3. Fraternal Order of Eagles Diabetes Research Center , Iowa City, IA 52242 , United States
4. Veterans Affairs Health Care System , Iowa City, IA 52242 , United States