All subjects had been recruited for the project entitled "Prevalence, Incidence, and Natural History of type 2 DM in a Health Area of the Central Valley", which was approved by the Research Administration of the University of Costa Rica project number 742-99-339.
742-99-339 de la Vicerrectoría de Investigación de la Universidad de Costa Rica: "Prevalencia, Incidencia e Historia "natural" de la DM en un Área de Salud de la Meseta Central".