Jackson JM, Defor TA, Crain AL, Kerby T, Strayer L, Lewis CE, Whitlock E, Williams S, Bonds DE, Vitolins MZ, Rodabough RJ, Margolis KL. Self-reported diabetes is a valid outcome in pragmatic clinical trials and observational studies. J Clin Epidemiol. 2013 Mar; 66(3):349-50.